Bellhousing, flexplate, torque converter, crossmember, longer driveshaft, shifter, shifter cable...Thats pretty much what it would take... i havent done it or researched it much....But i cant think of anything else that would be needed...
Reason you are going with a C4, from the people i have talked to, its a bad choice because our cars are so heavy...Look into a th400 ( turbo 400) might be better choice for you