I chose to use a 1999 S10 frame ($200 tires brakes, power steering, etc) as a donor for my 46 frame. You can "clip" the whole front end onto the 48 frame just under the front seat. Then you have IFS, disc brakes, power steering, etc. I removed the rear springs, and cut the shackle bushing out of the S10 frame. Then I cut square holes in the 46 frame just in front of the inside bumper bolt holes and welded the shackle bushing into those square holes. Use a lot of water so that you do not burn up the rubber bushings. The front leaf spring brackets are held onto the S10 frame by 4 revits each. I cut the revits off and ground and punched the revits out of the brackets. You will find that the brackets can be located just in front of a body mount on the bottom of the 48 frame. I chose to drill holes and use #8 bolts but you could weld them.
The S10 2 wheel drive differential is too narrow for the 48 frame. I bought a 1995 Impalla differential ($50) and cleaned it of mounts. I bought spring saddles ($16) from a trailer place and welded them to the Impala differential being careful to locate them at the same angle as the old ones on the S10 frame. Also you have to measure carefully so that you weld them the correct width apart where the springs match up.
The 48 car body will fit right back onto the 48 frame and you will have to fabricate the two body mounts that got cut off. They are the two located at the fire wall. This gives you the Independent front suspension, disc brakes, power steering, dual leaf springed rear etc., of an S10 without the problems of mounting a 48 body onto a lengthened S10 frame.
Reverse (use the right one on the left side and vise versa) the bottom leaf spring plates so that the shocks will slant forward instead of backward so that you can use the 48 gas tank. You will have to fabricate the upper brackets for the shocks.
There are several differentials that will work for you. I liked the 2:93 gears in the Impala differential. However that gives me different GM lug bolt patterns, front to back; but I can handle that. Also you have to fabricate mounts for the front fenders. I cut off part of the grafted S10 frame and welded a short piece of the 46 frame onto the S10 frame so that I retained the front bumper mounts.