Fuel injection on older engine

I guy wants me to take the engine out of his 1988 halfton 4wd chevy. He has a replacement out of an 1978 truck.My question is how do I use the fuel injecyion manifold on the older heads? Do I just modify the center holes on the intake? Are there any other problems I will run into. Such as flywheel to crank. Or distributer problems. ANy help from someone that has done will be greatly appreciated. I just don't want to start something and not be able to finish it in a day. Thanks in advance. Jeff