popops:

You didn't say what engine you had on it. But generally speaking, if the plane flies well at part throttle and you can't keep it from climbing at high power you will have to put in more down thrust. Problem is that when you go inverted it will work against you.

Best is to go neutral incidence on the wing, if it's semi-symmetric or flat bottomed it will appear to be negative, check it by putting the engine at zero down, test fly upright and inverted. When it acts the same both ways, you're balanced as well as you can.

And be sure the stab is at zero incidence, too.

Bill.