1st gen. Hemi to small block bell housing adapter?

I'm also a machinist , I can machine it myself. But I'd prefer not to, considering it's a stock item (as you mentioned) and someone could use it, or just polish it up and use it for wall art.
So you've answered my question, and now I know what I have.

I'd prefer buying the correct adapter/crank hub spacer/flex plate kit from Hot Hemi Heads.

Yeah me too. But the cost is holding me up.