Rcpilet,
I dont understand why your big glow engines where running out of torque. Where they overheating? A pump or regulator does not guarantee rich setting and sufficient fuel supply. I know some guys running fuels without nitro or very low % are having more trouble with the needle settings and overheating problems. I usually grossly overprop all my glow engines and use quiet pipes for two strokes as we have strict noise restrictions here.
My ST G3250 and a APC 20x12 @7600 would pull my plane vertical all the way to the moon if my transmitter was strong enough. That was just an example because all my glow engines will pull vertical until the tank is empty. Pattern guys are doing loops bigger than a fotboll stadium all the time with the 23-26cc twostrokes loaded down to 7-7500rpm at peak.