To give you an idea of the way this plane is designed - I have one and am flying it with a super tiger 2300, which is a 1.4 cubic inch glow engine.  this flies this plane VERY WELL and requires no tail weight.  I use a master airscrew 17-8 scimitar prop which it turns about 8500  on the ground and in the air it unloads to much greater rpm - probably about 10k.   A gas engine will weigh much more than this and will require tail weight.

This will give you an idea of the engine weight that just balances this plane with no added weight.

Ed