Kept original frame on my 37 and had a friend fabricate a cross member and used original Stang II parts from a 78 Cobra as it had the V8 and beefier springs. I have no problem with it on my 37 but at times I wish I had the bigger GM rotors which I can still use if I wanted to switch.
My 52 panel still has the straight axle under it but I did put power steering on it. Running Drum front and back. No problems and I can stand it on its nose in an emergency.
Think long and hard and take a look in your wallet before starting!