Why Nema34 and not 23s?

33v secondary will give 43 to 48v on supply variation which doesn't leave much room for regenerative dumping on a 50v drive. I'd go for 30v secondary.

Don't see how you'd reuse the toroid on an 80v drive. 2*33*1.414-1=92v +/- 5%, you need 2 x 27v secondaries for maximizing an 80v drive.