Stovebolt six exhaust valves are identical to the ones used in a lot of small block V8's. There's no point in paying outrageous prices to some resto-ripoff place for part number matching exhaust valves when stainless steel exhausts are a dime a dozen from lots of online suppliers. They're better quality and more durable than OEM valves, and they'll probably last as long as you own the truck. The intake valves are sort of oddball- - - -I don't know of a suitable work-around on them.
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
Love your enemies and drive 'em nuts!