take the si off your car huh? yeah it all depends were you live.im going to assume u live in california and i am going to aswer you as if you lived here in this crappy state.
you can swap a motor from the same year or newer car.you cannot have an obd 1 car and re wire it for obd 0 its vice versa.if you want it to be legal u need all proper emissions equipment required ni your state,if you pass emisions you still need to pass a visual inspection,a lot of people fail the visual for various reasons.personally my car is illegal as we speek i live in cali and have a 91 hb si with a jdm b16 swap,if for some reason a cop decides to be an ass and send me to a ref station then i will need to pay there fee for the inspection and make sure every thing is in working order,"i.e o2 sensores located in the right spot,good map sensore,throwing no codes,correct obd,correct ecu,just little stuff.my car throws a code for something but we never could figure it out.my ecu light just stayed on before i got it and every thing runs fine."i think it's just a wiring issue" any ways if they dont check your ecu in your area i would just take out the cel light in the cluster.but thats pretty damn rare.ok so if you followed through all my blabbing then you go get inspected and you get a stocker saying your good to go .put it in the door frame and your done..