The bellhousing shouldn't be a problem. As Al said they are a swap meet or junk yard item. An early pickup bellhousing will also work as long as you stay away from the ones designed for hydraulic clutches (the opening is on the passenger side). If your 400 starter is in good shape , find a 283/327 starter designed for the bellhousing and swap the tail shafts. I had a 400 in a '62 pickup and I used the 283 bellhousing. By the way, if that 400 is basically stock you'll need a 454 flywheel (they are externally balanced like the 400)