67 cuda convertible spare tire problem

I bought a space saver spare from a compact mopar, don’t remember which one. It is a 5 on 4 inch sbp. Think I paid $7 at pick & pull. My trunk board sits flat with it.

It is a lot smaller diameter than my tires, so likely be an issue for my sure grip if I had to put it on the back. The center hole is a little smaller, so that could be an issue. I had to grind it out a little to fit the front. The good news is that it is a big enough wheel size that it clears my disc brakes. I was thinking about geting a 6.50-13, which is what I think the spare tire well was designed for, but I was concerned it wouldn’t clear the disc brake calipers.