TKO 600 vs T56?

[65ss]

Ok I know this subject has been explored before. I haven't seen this question answered before though. Have a 65 Malibu SS 427 BBC roller cam, mpfi consevitive 525hp 550tq. Would like a T56 with a 4.11 rear, but am worried that first gear would only last 30 feet, and with the close ratio wouldn't have enough time in between shifts. Anybody out there running a combo like this? Would a tko 600 with a 3.73 be a better idea? Wheres the best place to get a good T56? Thanks for humoring my redundant question.
T.J.