Bidule:

If the plane acted pretty much the same power on and power off the thrust line will make no difference in its tendency to roll.

I'm almost sure your problem, as DC said, is a warped wing.

The good part, though, if you used any form of heat shrink, whether fabric or film, you can heat the wing covering, while holding it twisted opposite to the warp, and take it out.

Might take you two or three tries, try to get half the warp heating the top, and the other half heating the bottom.

My last high aspect wing was a Goldberg "Electra," I set the washout in the wing with a heat gun, exactly as I explained here. Or I hope I've explained it.

Fix it, enjoy it.

Bill.

PS: If you want it to be aerobatic, leave the engine thrust line zero-zero. Offset thrust makes it act differently upright and inverted. wr.

PPS: DC, just noticed your sig line, "Klaatu barata nikto." Michael Rennie and Patricia Neal. I have a tape of the film. Did you ever read the story it was based on? "Farewell to the Master." wr.