.016 to .018 is fine for the top ring. In the old days we gapped the second ring tighter than the top figuring it did not see as much heat.But we have found that a larger gap on the second ring allows traped gas to excape and allows a better ring seal. =more power.
so second ring gap .020 to .022
Allways check the oil ring rails for gap this can vary alot sometimes from .040 to .080 or more. I like to assemble the piston in the bore with the oil ring only and "pull" the piston with a fish scale. The oil ring is a big culprit in excessive engine friction. Be very carefull and you can adjust the oil ring bracelet to adjust the pull.Then check pull with all the rings.