Ok, I couldn't wait. I measured the hole in the main cap and it was .470". The drill required is .453". That means I can use the hole as a guide and if I line it with some .005" shim stock, that will leave me with .002" of slop for the drill and that is more accurate than most drill presses so I should be ok. I'll still call my machine shop and my grandpa to see what they say.