Thanks all, I made those little brass plugs on the lathe, the exhaust plug even is threaded at 9mm x .75, the intake plug is a slightly draggy slip fit into the pipe hole and the actual intake port. Fun can be had in the most unexpected places.
Those coatings sure look nice.
PS: there is actually a place in Fredericksburg that is licensed to to Cerakote:
https://www.ssgtactical.com/