About the transmissions... just realized you have a 3 speed. That is probably a better transmission than the 4 speed crash transmission. The 46 bell housing has a different transmission bolt pattern than the later bellhousings. That limits your choices to an original 3 speed, or an original 4 speed. If you lose the torque tube you will have a few more choices for transmissions.

Don't forget about the brake and clutch pedals that bolt to the bellhousing. 47 and later bellhousings do not have the mounting boss for the brake and clutch pedals.

John