*goodness...
i hope u can understand that with all the electronic sensors, relays, etc... that modern engines have these days... transplanting requires the literal "TRANSFER" of ALL... and i mean ALL the the electrics that go with engines.
gone are the days of the 60's and 70's when all u neede to do was drop in the biggest engine you could find and pop it under yo' hood!
SO... the only way to do a trans[plant with 80's engines is to locate an intact M3 and move all the parts to whatever it is your car is...
SANE?... i dont think so.
WHY?...
1) it's easier to buy an M3 and not pretend to be an M3
2) if u are not an M3 but wd like to perform like one, there's maybe a 107 + ways to make your engine perform better than M3 without having to foot the bill of puchasing "2" cars.
3) where is the logic in what u intend to do?
am nt trying to put u down on ambition and pride... but take a second look at yo' pocket dude... both in expense and in resale value down the road...