If you really want to fly a Testors, try finding its predecessor, the Wen Mac, which was available with a head that took a standard short reach glow plug.

I have a Wen Mac .049 mk2 that is a really easy starting sweet running little engine. No powerhouse - about 15,200 RPM on a Cox 5x3 - but super easy to start and tune. Its going in a Walt Musciano designed control line model, probably the Stunt Master from Blackhawk models.

cheers,
Colin