Assuming all is stock under his car, he's already got the B & T, it's a '65 only deal. Kinda tough to convert the B & T style to u joint. No way I would suggest changing to to that style. I'm just saying for convenience, rather than finding an entirely different set up, just rebuild the current 904 and stay with the B & T. I just posted the pic for reference.
Again, the one issue he's going to run into when installing a later trans is finding the correct length u joint type driveshaft. Prolly wouldn't be too hard. In fact, I'm willing to bet that someone somewhere is yanking an entire Slant driveline out of an early A right now and would probably be happy to give this guy the parts before they threw them in the dumpster...