If you shoot bare shafts with a canted bow, as Don suggests, then just do a mental adjustment for the amount of cant. If you're shooting with the bow canted to 1:00, then an arrow inclined toward 1:00 would be "nock-high," and not "nock-high right."
I prefer a little nock-high when I bare shaft rather than perfectly straight, as the fletches easily and consistently correct a little nock-high, and there is less likelihood of any bounce off the arrow shelf.