RE: norvel engines
NORVELs were manufactured in two versions, the AME which had 3 oblong intake ports and the Big Mig which had 5 basically round ports. The AME was the high performance engine - a little less user friendly; did not throttle quite as well on the low end and it tended to turn a higher RPM.
Both are ported for higher RPM and each model should not be over propped -- the 5x3 works well. You will probably want to run 20 to 35% nitro and around 20 to 22% oil with a good portion castor.