I know that you have your mind set on adapting what you already have, but there are plenty of correct bellhousing out there especially if you look at all of the SBC and LS swaps that have been done. Have you thought about the clutch linkage? What about the foot starter. If you are keeping that, you’ll have to adapt that too.
IMHO, post an ad in the “Truck Parts Wanted” forum for the correct bellhousing. I found a replacement for a cracked one on my ‘52 that way, shipped to my house.
If your still intent on adapting it, what Bartamos posted should point you in the right direction. Good Luck!
