But it's a band-daid and band-aids almost always bite you in the ass. If the wheel is not grinding reliably, so you resort to some tricks to keep it from digging in, then it also will never repeat. Then getting the size you want is just a matter of luck. That's not a great approach... as the wheel goes through the interruptions it deflects. If it deflects down it suddenly has a greater bite, where if it's a touch above center that's not as likely.
Pulled out the calculator, actually your wheel speed is only a few thou below "generally accepted priciples", that's nothing to worry about. Lesson : don't do math in your head But I keep thinking Borazon would be better, it is much sharper than oxide wheels. Haven't done enough chrome to make a definitive statement on that but I'd give it a try. Or diamond. Or Cubitron II. Something less likely to skate across the top.