My vote would be go with Hurst Driveline Conversions in Ca. Professional and top notch service.
In my experience they guided me to purchase the correct tranny, clutch and hardware needed for my t56 in my 69bird.
Another vendor sent me the wrong parts needed for my LS swap/t56. No big deal, but the vendor picked all the parts out and when I sent it all back I had to pay for restocking fee's $60.
Hurst also gives great tech support!!!