Stock 340 forged crank/A727 converter - Who sells a good one?
On cranks, just read what the material is made of.
The MP cranks were often 5130 I think it is which is fine for most applications. The very hi performance ones are 4340. Oddly, at least in my head, my 3.545 MP crank designed to make a 352 w/a 4.03 bore size is a 5130.
(If those are the correct numbers for the forging.)
I have had several fellas tell me they have run in the low 9’s with that displacement and crank.
On a transmission, I don’t think I can help. B&M and TCI have a basic rebuilt units. That’s a choice if a local shop is not available for this service. Though VOETOM (above) has a book out of how to rebuild a 727.
(I should have had him sign it.)