My valve grinders are so ancient they have the attachment for cutting flathead Ford stems to the right length for non adjustable lifters and another grinds a crown on the bottom of a used lifter. My favorite is a Tobin-Arp that grinds on the side of the stone so a worn out stone cuts at the same speed as a new one. One not used since circle track days is a Black and Decker dry grinder that one had to go very slow to prevent heat but left an absolute mirror finish. Lapping pattern showed instantly. We used all intake valves cut back to exhaust dimensions as they would bend but not break. Probably wouldn't be a good idea on non-alcohol engines. Used many used valves that measured within specs.

Evan