Won't matter what the original motor was. Both of them will be about the same to put the 302 into. The biggest decision you'll have to make is coil or leaf? square or round?
You will probably want a different transmission though. The AODE (new for 1991) is electronically controlled by electrical solenoids controlled by the PCM. You might be better to find a pre-'91 AOD if you want overdrive, or even a C4-C6 if you don't need OD.
If you want to keep it super simple, dump the EFI and PCM in favor of a carburetor and intake.