Matt,
If you use a TF V8 Bell housing and these front V8 mounts it will bolt right in.
http://www.classicparts.com/1955-59-Original-V-8-Conversion-Set/productinfo/79-375/#.Vlz2xnarS5cThe T-5 will hang off of the bell housing (others will need to confirm the trans bolt pattern on the T-5 is the same as the SM420).
I have this set up in 3 of my trucks all running SBC's.
Note, I left the radiator in the 6-cylinder position on my '56 3100 and installed a 16" puller electric fan...works great for me.
Mike B
