Some downthrust would not hurt but a strong power related pitch is often a sign that there is too much up trim or wing to stab anglular difference (called decalage) to compensate for a forward balance point. Moving the balance back requires adding down trim and that will reduce the power related pitch reaction.

For a GeeBee I would inquire with other owners as to where they balanced the model. Or if you wish to experiment with this yourself then move it in very small increments like 1/4 inch at a time until the model can be dived at low power and upon stick release will pull up to level over about a 200 foot elevation change from a 45 degree dive. If you can dive it like this and it pulls up more sharply then it's a good sign that you are balanced too far forward. Moving the CG back and retrimming the elevator will lessen the power related pitching problem.