I have whipped out a drilling template for .21 CMB motors for Speedmaster mounts. If you would like one I can send you one for a couple of bucks to cover the shipping. This one was made specifically for the dropdown mounts that Jerry uses in his boats.
Sounds like a good idea! Better than trying to line up an engine. Or, maybe an added check to make sure where you have marked is correct!
Final price sent to 48892. I'll send a separate email w/addy.