Well, I've been accused of being old school and I'm guilty as charged. I have the machine shop grind the valves on 3 angles like Matt alluded to, but then I take 'em home and lap 'em in myself with compound and a suction cup tool. I've had guys at the machine shop give me grief for it, saying that their grinding job doesn't have to be lapped, but I'm gonna do it anyway. Always have, always will.