Hy Judson, yes you should check both specifications, if your working with a freshly bored cylinder and new pistons the job is a little easier. Use a piston inverted to position the piston ring square in the bore to measure the end gap, measuring the ring groove clearance involves holding a ring in the appropriate groove and measuring the clearance with a feeler gauge. Should you find your end gap to be too tight they can be "filed" to increase the gap, a word of caution if you happen to have "moly" filled rings I would take the rings to an automotive machine shop to have the pros make the needed adjustments, hope that helps.
