Just build a regular plane, but finish with Rustoleum and worry more about getting the finish nice and even instead of weight. Then you'll need so much weight in the nose that you'll welcome an overweight engine.
Seriously, you're spoiled for choice. If this is for stunt don't worry about radial engine or not, particularly if you're building a profile -- just whack off the nose as you think appropriate and proceed.
Boeing "Peashooter", Republic P-35, Monocoupe (if a Piper Cub can be competitive in stunt, why not?), Westland Lysander, F4F, F6F, Republic Thunderbolt -- and that's just what's coming off the top of my head.