Hand-lapping valves went out of favor back in the early 1950's. I'd strongly reccomend subletting the head work to a machine shop, especially since stovebolt heads without cracks in them are very scarce items. A comptetent machine shop will pressure test and/or magnaflux the head first, before doing any rebuilding to it. Valve stem and guide wear needs to be measured, also.
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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