depends on wat engine ur gonna transplant, if ur gonna transplant evo 4 engine, here's my experience.
plz make sure the halfcut is in good condition, bring ur mechanic along
leave the car in the workshop for sometime, let them do it nicely, as the wiring will take quite some time to do
since ur already dismantle the car parts, take time to do it nicely, change ur cluth plate, take ur rear disc and convert to five lugs unless ur mechanic can mod ur evo4 rear brake to fit
dashboard mounting must weld, cant simply fit, and u have to cut ur door trim or either ur dashboard in able to close ur doors
take ur whole air cond system, send it for flushing and u wont regret later on, but make sure ur compressor is clean and in good condition
top overhaul, do it, change ur head gasket and watever gasket that need to be replace.
locking ur 4wd to 2wd gb, haha that u have to find specific workshop to do, not many ppl can as claim to me, but end up slipping, i can recommend u the workshop if u want to
u need to get new set of rims, coz evo 4 runs on 5 lugs, and dont use the ori evo 4 abs as u will feel ur car like sampan, its very stiff and high
fuel tank, try to mod and fit in 4wd tank, if not u wont have petrol reading with original float, and u have to custom a bracket inable for ur evo fuel pump to fit in the tank.
thats all i can remember for now, maybe u can ask other sifu to help u on this.
goodluck =)