I got it in!

I used the TTI headers. The gap is 1/2", a lot better than 3/16" but still not a lot. I don't expect it'll hit, but I won't know for sure until the first time I dump the clutch (can't wait!!!)

I didn't like the way the TTI mounts interfered with the factory A/C compressor and oil filter so I wound up making my own mounts and doing some fabbing on the K to make them work. I can't comment on the shim situation, but I would suggest definitely getting the steering column in before finalizing the engine position.