Use a cast iron bellhousing, and you can probably get away with having no support in the bellhousing area. I wouldn't even consider it with one of the flimsy aluminum ones the later models with the 3-point mounts used. The first big bump you encounter might get exciting when the bellhousing breaks. The original Hurst-style mount also prevents the engine from running a mechanical fuel pump unless you cut a hole in the mount for fuel pump clearance, and even then, changing a pump becomes quite an adventure.
Jerry