Yes 320 grit with the flexhone as you wouldn't want to use a 3 fingered hone unless you had a dial bore gauge and they are hard to use properly with a hand drill. Critical is following KB's piston to wall recommendations and .0065" per inch of bore on the top ring end gap and regular gap on the 2nd ring (I like .003" per inch of bore). I'm assuming reringing going from OE cast pistons to KB's? You said the shop is not miking your bores, Just make sure your P/W clearances are adequate and KB's recommendations are critical. Google the dingleberry honing procedure and check out "breakin secrets" at www.mototuneusa.com. #1 dish soap and water clean the cyls taking plenty of time but working fast so you can thoroughly clean it and get it oiled and one cyl wet at a time so the others are not flash rusting while waiting their turn.