given that when you punch car details (i.e. vehicle code: U13, trans: Manual, engine: SR20DET, Spec: SSS-LA) into FAST and it doesn't require a year, I dare say there could not be a different for any part numbers and therefore engine specs?!?!
i highly doubt it'd be different, sure on a U13 not many (any) people would have pulled a red and black top down side by side to compare, but on a S13 it's sure to have been done. the engine side of the loom MIGHT be different but i doubt it, in the car it wouldn't though. the other ecu would likely plug in fine anyway.
on top of that, a bench top power supply, a consult plug and a computer and you could easily pull the maps out of each and do a compare on them, simple.