Well, you’ve gotten 3 different ideas of what you need, basically you should go locate the internals first, the Naomi system, and the MvC2 cart… and any I/O or jamma boards to support that.
The Arcade Otaku forum is great for that kind of stuff, and thebluedino has offered to provide more assistance if you need it, perhaps over IM where you can talk and ask questions that might draw flames…
For Happ hardware at a great price, I got all my stuff to freshen my SF2 HF cabinet from gthomp1@cox.net. I found his name from the BYOAC (Build your own arcade controls) forum.
I bought this two complete sets for the cabinet and another for a custom xbox stick I made. Quick turnaround too. Google him if you need verification. Also, I have a Capcom USA SF2 HF cabinet that I’ll gladly measure if you need.