I am rooting for you, belive it or not
I think getting it demonstrably rolling would have tremendous value for the EV community as
these things are sitting out in the elements (and being scrapped) and plenty of people would be very pleased with the stock hp levels at the $400 price point. So it is your basic "the great is the enemy of the good" kinda thing IMHO.
Also 650 volts, despite the benefits, is kinda nuts in a DIY, nothing will charge it that I know of ('cept multiple isolated). Even the best dragsters aren't much over 400v. Maybe some of those connecting red/yellow/blue wires can be brought together to parallel some of the coils and cut the voltage requirements in half.
Also there is some question as to how much you can actually overamp the magnetics, as well as if the differential itself is a limiting factor in beyond stock power delivery. I wouldn't expect any miracles from a differential designed for 60hp.