when the front end was done, did they install a crossmember for the control arms to mount to? (I'm assuming here that you have some sort of control arm style front end, maybe tubular construction control arms similar to a mustangII setup?) if so, drive the car straight onto a level floor, without turning the steering wheel at all if possible. this will ensure that the frame isn't being torqued up from turning, and the car will be sitting at ride height. then place a level on that new crossmember (don't jack the car up or you will skew the results), front to rear and side to side, say under the engine. it should be level. also, place the level on the lower control arm front to rear. it should be level as well, as far as I know. also, is the lower control arm level from left to right? these things could have a bearing on steering angles if they weren't set up right for your ride height and rake angle (the angle the car sits at from front to rear). like if the rake angle was set up to be 3 deg, pretty common, and you get it home and decide you would like it to sit level or jacked up or down in the rear, then that would throw out the built in geometry from when the front end was welded into the car. also, if the lower control arms are not level to start with then as they go through an arc, as the wheels go up and down over a bump, the track width changes (tires actually slide out and then in (side to side the wheels get farther apart, then closer together) as the wheels go up and down. that would have an affect on the toe in.
if you had the car jacked up and turned the wheels from left to right, and got a tight spot in the middle, try disconnecting the steering column shaft and do it again. maybe there is a tight steering shaft bearing or something is binding or bent in the column. when you have the column disconected the steering wheel should turn 360 degrees with ease.like if you gave it a spin it would keep going for several turns. maybe a good idea to take the lower u-joint off the shaft and leave the shaft in the centre support bearing (if equipped) so you will get the best "as driven" model. is the steering column a tilt unit? does it have the same tight spot if the column is not tilted one way or the other? maybe a phasing problem with the u-joint in the column and the u-joints in the rest of the shaft external to that.
if you still have a tight spot with the column taken out of the equation, then stop it in the tight spot and look for anything that is binding obviously, and do a check on the steering box adjustment. especially if it is tight in the middle of the steering box travel, the box could be adjusted too tight. if there is play in the box then it is likely another part in the front end that is binding, tie rod end, idler arm, ball joint etc.
the next thing to do would be to disconnect the tie rods one at a time from the steering knuckles and make sure the wheels turn left to right freely and easily independent of any other linkage. if you get a tight spot on one wheel then look at ball joints for binding etc. they could be distorted when pressed into the control arms, or just plain defective. check if the upper and lower control arms are in the same plane with easch other. when the tie rods are disconnected from the steering knuckles (at the wheels), then the wheels should flop around very easily.
if everything on both sides checks out good when disconnected and checked independent of each other and the rest of the steering system, then look at the rest of the components independently. turn the box by hand while the column is disconnected and try to determione if it is in the box or another steering part. you could have a bent shaft or a tight bushing ( I have seen those shafts actually twisted at the splines from hard offroad driving. you don't know what that rebuilt box has been through since 1977 or whatever year it was made). you could disconnect the pitman arm from the linkage and take the rest of the linkage through a full left to right turn to check if that tight spot is still there with the steering knuckles and the box out of the equation. also do the full left to right sweep with the steering box all by itself while everything is disconnected from it. start up the engine and do the same thing all over again, maybe a valve problem in the box.
to answer your question on why do a four wheel alignment. a good front end alignment shop will try to convince you to do a four wheel alignment because it references the front wheels to the rear wheels. that is, it makes sure that the front wheels are running in the same plane as the rear wheels when the vehicle is set to be driving straight down the road. it eliminates the dog tracking thing. otherwise you are just aliging the front wheels to themselves and the rear end follows wherever it will. you could compare it to the little red wagon that little kids drag around. the front wheels could be set up awesome, but if there is a problem in the rear, like if the rear axle isn't parallel to the front or if the wheels have a bunch of side to side movement, then that little red wagon isn't gonna steer all that good no matter what you do to the front end. on large trucks the rear axle spring pins actually have shims on them, and if not shimmed fairly tight the truck will drive just like your car. by the end of the day the driver is worn out from sawing the wheel back and forth all day. the shop would also make sure the box is centred and adjusted correctly, the steering wheel is straight ahead, all the front end parts are within specs, the rear suspension pivots and rear axle to spring mounts are within specs, the bumper height is correct, etc etc. you gotta understand though, if you take your vehicle in for an alignment and don't explain to the TECH, what is going on, then the tech will assume that it was all fine to begin with and the alignment is just routine. lots of the techs are on commission, so the more jobs they can do in a day the more cashola they take home at the end of the day. it would be best to have the TECH, who actually does the alignment, go for a drive WITH YOU IN THE CAR, so you can explain to him, and he can see first hand, what is going on with the car. sometimes the message doesn't get to the tech, or the service writer who takes the info doesn't understand whats really going on. lots of the service writers don't really have a clue about mechanical things, they learn a few buzz words and talk the talk. best to ask for the shop forman or better yet, if you could talk to the alignment tech who will be doing the job.
not trying to slam anybody here, I have just had those experiences myself over the years. usually a misunderstanding between too many people in the loop.
anyway Bob, good luck and keep us posted. if you can snap a few pics of what that front suspension actually looks like that would help. sorry for the long post, sometimes I get off on a tangent.....