I beadblast valves all the time. If you're concerned with creating a rough surface on the valve stem, slip the part of the stem that runs in the valve guide into a piece of rubber tubing. (vacuum line, fuel line, etc.)
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
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