Great info folks, I appreciate it.
I got it running and it actually ran really well with the new intake gasket, purred like a kitten. Doesn't even seem to smoke. Unfortunately, as it got hot the intake started leaking again (for the reasons I learned in this thread - 49 intake, small ports on a 57 head with big ports, and only the small rings just floating around).
So I'll be machining new adapter rings for this mismatched unit and ordering those better gaskets.
I'd call this "solved" at least. I'm glad to know the challenge and deal with it.