Yes, the QB and the TD09 have the same threads in the cylinder towards the case and glowhead. A brass bushing could be made for the low-end, I guess, but one would also have to consider timing and compression ratio. I haven't checked the stroke, are they the same?
Considering how hard it is to find a good piston liner for a TD09, one might as well use the TD engine and put throttle on the exhaust. Even the TD09 RC is in fact slightly lighter than a Queen Bee...!
