you will have to go by the fitting thats on the oil cooler, for bigger and smaller cores there will be bigger and smaller fittings if you get me. once you have that then work your way back to the block. im assuming your making your own kit up is it?
also get yourself a thermostat to go in relay for your system, most times its going to over cool your oil the thermo wont let it enter the core unless it needs to be cooled