Extracting the valve is easy. Remove the head. Remove the springs. Grind around the tip with hand grinder. Valve falls off.Somethings wrong with the geometry on the #1 intake. Look at the shiny wear marks on the rocker stud down by the hex, that shouldn't be there. And someone will probably have a fun time getting that valve out. It's not worth the asking price.
Yes, it looks like the valve for the #1 exhaust is for an early, non-rail rocker arm and the other valves have the taller stems for rail rockers. Offset wear marks looks like wrong length push rods.#1 exhaust seems to have a different installed height ont he valve, could be something very simple. I see screw in studs & guideplates, so it could be a performance built set of heads. If it comes with the valve covers, intake and carb, you can't lose at $500.
And if the keepers are stuck: With the springs uncompressed, placing deep well socket on the retainer and giving it a quick rap with a hammer often pops them out. Granted, the mushroom should keep the valve from completely dropping, but one should have the piston up in the bore to stop it from going too far, just in case. It takes a little finesse and it's best to have a glove on so that you can hold the socket and the edge of the retainer so that keepers do not fly away and you do not pinch your hand between the spring and retainer.Too easy. Compress the spring, and the retainer goes downward, away from the mushroom. Then the keepers fall out. Not my first time at this particular rodeo.