You never know what you're going to have with a conversion, but it doesn't sound odd to me that you'd be tail heavy when converting from glow to electric. After all, the motor is lighter than a glow engine and you have that heavy battery that you can't put on the nose. If by a heavier prop you mean going to a glow prop instead of electric, don't. That will noticeably hurt your efficiency. A weighted spinner could help a bit by putting the weight farther out forward, assuming you can get one for that motor.