I wouldn't mess with any of the head-on-engine stuff unless it was an emergency repair to get the truck back in service. This doesn't seem to be the case here, as it is serviceable, albeit smokey. Also, I am lazy and would rather work at the bench than leaning over the engine. Just pull the head and have the guides replaced and the valves replaced or reground as needed. No seals necessary this way. To speed things up, have another head ready to install before doing anything and it will take less time to switch out the head than to mess with doing anything with the head on the engine.
