Steve,
Some folks don't follow the "1 Turn" from noisy rule any longer......something about lifters pumping up causing havoc....where if you go anywhere from 1/4 turn to 1/2 turn you can have less pump up if it did actually happen..... It's supposed to do something else also.. probably related to geometry of the tips of the rockers and the valve stem......but can't recall it....brain is fuzzy. I ran 1/2 turn on my old 351W rockers and 1/4 turn in my Goose with no issues, but then I set that up on the engine stand where I could check the actual lifter piston to retainer spring clearance while I was doing it. No hot mess!
If you read the Ford procedure for determining push rod length, where you collapse the lifter and then check clearance.....then determine what that length is, and then calculate the "length" per turn of your rocker stud nuts you could get an idea of what Ford was looking for......but that is a total PITA!
You're on the right path now!
I usually just use cardboard bent up and around the inner lip of the head, the one side of a gasket set box seemed to work well! Just no over rev'ing!!! Keep the idle down...... maybe a little drippage......but nothing to be too concerned about!
Rocker on!!!
Steve