OK, the '46 truck bellhousing and the modern trans:
These units were used on all Chevy trucks from about 1938-47 and have cast-in mounts for pedals/master cyl bracket. Also the transmission bounting holes are closer together so none of the 50s tranys will bolt up.
The easy fix is to go to the early 50s truck housing, which has the later trany pattern, same rubber mounts etc, but no pedal mount. However, the best solution around when it comes to using the T-5 trans with it's longer input shaft, is to keep that 40s bellhousing and use Buffalo's adaptor plate. With this adaptor the long T-5 input is not a problem and you'll not have to fabricate new pedal mounting surface. Buffalo can be reached at (360) 652-7684. What he lacks in the catalog dept. he more than makes up for in solutions to any and all mods for early Chevy trucks and cars. His workmanship is first rate.
I hope this is the info you needed [censored], just get back to me with any other questions.