Good morning Jerry.
I haven't seen your tool co I can't comment specifically on it. If I were going to make one it would be a simple sleeve with a stepped bore. One bore to slip over the crank snout and the other smaller bore to act a guide for the appropriate tap drill for the threads I was going to make. For a single use or very occasional use anything beyond that, like a hardened drill guide, seems like a solution looking for a problem.
That seems pretty simple to me.
