I would hope that not too many modelers subscribe to this practice of plumbing tape thread and, seat repairs. Reminds me of auto exhaust repairs with muffler patch,and bailing wire.

Take a look at this NGK tutorial. You really should get/make a flat seat style adapter, or have a Buddy add the taper to the seat as was suggested.

Partial NGK quote:
"The spark plug works as a heat exchanger
by pulling unwanted thermal energy away from the combustion chamber, and transferring the heat to the engine's cooling system.

http://www.ngksparkplugs.com/techinf...000&country=US