FWIW

I would call a reputable custom builder, and buy a good one

You've spent some decent money on a stroked small block, and beefed up a 904 to handle it, why would you look for the cheap way out now?

Lenny at ultimate converter has an excellent reputation, and there are other companies who will build for your needs.

ALSO, a converter from a reputable guy won't cost a bunch more money, as he will still only sell you the converter you need. Not something exotic that you won't need. Just a nice, well built piece.

Buy a good converter, and you won't regret it.