OK so The plug is out and I could have someone tap it.
I could get two new heads (this is a good running motor and tapping would be a band aid in my opinion) and find someone with a shop to relaced them both, all for about 500.00.
OR
Find someone to build my New engine (with some old parts, some new parts) for which I will need to get a Flywheel, engle110, other miscellaneous parts. this will cost more, but how much more?