Robert, this is what Glenn Quarles sent to me on that subject though mine has a modded NR carb, OS needle and a 3280 pipe:
4 turns out seems like a pretty good place for the initial crank up...if it doesn't sound crazy rich for the first tank (on the bench) then richen it up.
For the pipe measurement I go from the side to the head straight back to the high point...4" is a very consertive setting, 3.5 inches is probably around where you will end up.
Remember...make sure it gets up to temp during the breakin. I don't use any water cooling for the first runs (maybe 10 or more runs) until the needle is lean enough that the motor is getting too hot to touch after you bring it in.
