Sorry if I've missed it, but what exactly is wrong with the shell of your 1J'd car? Unless it's got terminal rust problems I can't see the justification of swapping shells, or selling the 1J'd car and running the Turbo in a standard condition.
Surely it'll only take a small bit of elbow grease and a few dollars to tidy the 1J'd car up? Maybe you could even pillage parts from the new one you bought?