Alright, so, l've done the legwork on researching RV 440's since I just completed the install of a 78 Motorhome 440 in my 64 Polara. Here's what I have repeatedly confirmed as fact. The later blocks have thicker webbing around the main journals. The 452 heads that are on your engine flow as good as the 906's on a flowbench through 5500 rpms but have the desirable hardened seats, ...use them. The wrist pin is moved up in the piston somewhere between .080 and .150" (reports have been conflicting) to bring the compression down to an advertised rating of 8.2:1 (actually closer to 7.9:1). New pistons and rods will be required to rectify low compression. It will most likely be cast crank which is identified by the bevel on the front of the thicker harmonic balancer (referred to as the bullet shape and it actually says "cast crank only" on the front of it). That crank should be good for over 500hp. 440-1 through 440-13 or whatever is just the number of times the particular casting pattern had been revised or repaired and has bears no importance on performance or design for that matter. The headers will fit, the length will vary because the truck motor mounts are very tall. They're going by application and not engine. The flange design is the same. Some people have said to watch cam lifts over .550 because there are no valve reliefs in the pistons.
Mine got a summit (crane made I believe) cam and lifters, oil pump, freeze plugs, timing chain, oil pump, distributor ($38 at your local auto parts store. The advance diaphragm will probably be dry rotted and leaking) and an AFB. Should be good for 325 to 350 hp and in the ballpark of 450 ft. lbs. I figure. Remember, they rated nearly all horsepower at the rear wheels starting around 1972 for insurance reasons. I did a lot of research before converting my ride to BB power. New trans etc... My engine was immaculate inside as motorhomes tend to be extremely low mileage and well maintained. Hope this helps.