Can you post a picture of what you have so far? You might also get one of those transmission adapters for an automatic and then change it to brace the manual. I take it you have a 216?

Example is that I put a 292 in my 59 truck. Bought universal mounts for it, but I have a 1 ton truck and the frame is wider and bigger. So I cut the ears off that would weld to my frame, and then I put the engine in where I wanted it and then welded on new 'ears' with 1/4 plate.

You might have to do something like that.