Mitty, If you are not familar with spadword and their Biguns (Large Scale Spads) check them out.
http://spadworld.net/forum/viewtopic.php?t=9321 is a trainer with Echo power. Mine flys like a trainer at 12#. with a CH Ign.

For my glow gas engine experiments, CH Ign http://www.ch-ignitions.com/ supplied the glow adapter. Discovered upon reciept that they did not fit properly in the heads; No problems with CH service; they had some replacements Express / Priority Delivered to friends who hand delivered South of Border. Super service as usual. THANKS.

I tried to make som plug adapter with only limited sucess, the wall thickness is thin. Clearance is minimal. Not worth the time for me to try an make more.