I have 2 1960's A's and a 1965 C-body. I bought the C in 1991, when it was only 26 yrs old. I had a 1969 Dart at the time. Some parts interchange between A & C of the same year. I have a 1965 Dart. Of course engine & transmissions are the same, though B/RB engines were rare in A's, but popular in B & E so many parts available including much tuner stuff. Door handles, instrumentation and controls and such often interchange. There can be as many differences between same body cars of the same year, dep on 2 vs 4 door, 6 vs 8 cyl, brakes, etc. Don't worry too much about interior. Worst-case, you could follow custom builders and design your own dash and interior, though most instruments can be fixed. I put front seats from newer cars in my A's for safety, low-cost, and to get power seats.