On this swap the motor that's in front of your bell housing is not the issue. With your old trans pulled you'll need to compare the input shaft length, splines and the length of those splines, front bearing retainer, then clutch disc itself. If the splines do not extend back far enough as compared to your stock trans, the disc will not have room and will get bound up. You can extend the spines, not and easy job, or modify the disc. This is where you need to refer to the tech articles around.
I'm using a T-5 in my 46 pickup, used an Astro van clutch disc from NAPA(10 3/4"), same size as old unit but spines for the S-10/astrovan T-5. We used a spacer between the trans and bell housing, this saved us from having to shorten the input shaft or messing with the splines.
Again, just make sure your T-5 input/clutch disc will fit exactly as did your original unit. I can say this swap is probably the best mod I've ever made in this old truck. The T-5 is a 40 + year leap in technology over the original granny box.
