I used a '66 Saginaw 3 speed. It was a challenge to make the levers and shift rods to work. I drove that for a while and swapped it out for a T-5. The rest is history.
I would not bother with a non-stock 3 speed. The T-5 swap is everything that they say it is and then more. Awesome swap, no question.
Carl

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission