Scar, lap the crankshaft to the case with scouring powder mixed with oil....then run 50/50 synthetic / castor fuel up to 25% total oil. Your Norvel will hold a good needle setting if you do this.
Amen to not messing with the needle......unless the engine flunks a pinch test. I always set the needle with the nose pointed up. Did you know that with most 2 needle carbs the high speed circuit doesn't take over fully until the throttle is open 75-80%?
If you make a change, like nitro %, prop size, head clearance, etc. that forces you to open the needle, then you have increased horsepower. You will see the need to open the needle as an engine breaks in...because it is developing it's max HP. After a few tanks, most engines should be settled in.
Guys who overprop their engines will need to tweak [needle-dick] more because that's how it works.
Running supplemental castor in your fuel can contribute to more consistent runs, if consistency is a problem. The culprit is sometimes a runaway heat condition. I'm talkind about applications where you are "pushing it".