I would take a hard look at the timing. Seems to me that the first ignition should be enough to carry it through to the next firing cycle. How can it run if the second ignition point is not reached because of bounce back. Sounds like you have more than enough compression, maybe too much. These old engines were low compression. Just my two cents. Rickso, it fires and hits next compression and bounces at this point. I think maybe it's just fuel /air mixture, but I have no control over what goes in the cylinder.
the big question, is, what would you all do? should I give up on gas and fit a bubble or surface carb? or should i keep looking for better gas control and fit a carb with a needle for propane? someone here will know. unfortunately, there's not much written or published about this engine anywhere. the few pictures I've found on the net are mostly carburettor and spark, so I'm very glad I didn't make it the original hot tube ignition. would appreciate some feedback.