All of this you ask for is super rare. I would call Advance Adapters and put a TH400 or 4L80 behind it. You'll never pull the transmission again! And if you do end up going V8 you'll already have the TH400 or 4L80.
If you do end up sourcing the C4 stuff...make sure you dial in the gate shifter with the detents in the transmission or you'll fry it real quick.
Message me if you have questions.