I believe one difference is the addition of EGR to the 1993-95 plenum. So your early one won't have that. I also believe the ports to the injector housings were wider on the later ones?
It's my understanding it would physically fit, though. Just that it might not be very ideal. You could always buy some injector housings (they are actually not uber expensive) and have your extra plenum and IH's ported, and keep your stock ones stock.