I am restoring a 1955 Buick Super 56R Riviera 2 dr hardtop. The car is mostly disassembled, I am currently grafting in a '91 Caprice (GM B-body) rear frame stub notched to fit inside of the stock Buick X-frame. Works out very nice, after some fitting the cut '91 frame stub slips up inside the stock '55 frame and is fairly easy to weld in - very nice to have the tri-angulated 4 link, heavy sway bar, shock mounts, e-brake mounts, and a GM 8.5 inch posi with 3.08 gears. I have a '66 Riviera 425 nailhead and switch-pitch TH400 rebuilt and ready to install.
I just inherited the 1952 chev pickup my grandfather bought new - 5 window, short bed, non-original 235 stovebolt 6 cyl. I hope to use the 322 V8 out of the 55 Super in the pickup with a 3 spd column shifter and Saginaw transmission, will probably try to preserve the stock patina with a little fresh chrome, wide whites, and artillery wheels.