does anyone sell slightly tilted ex manifold spacers?

IF you have it angle milled, the guy doing it can easily spot face and redrill (at the same angle) the mounting holes.

I actually did something similar to the way you originally asked about. I milled and drilled some angled spacers for a set of custom headers..... but it only worked because the headers had the Stahl mounting pattern. Spacers bolted to the head, headers bolted to the spacers.
I don't see how that could work with stock manifolds.