If you want to get the head back to oe specs, take it down to a respectable machine shop, and tell them you want to reseat the valves, and while they have it apart, to R&R the valve seals. You should also have them check the deck to make sure it is within spec re. warpage limits. A quick resurfacing of the head and a hot tank, then reassamble, and you should be good to go. A machine shop will usually charge around 20 bucks a seat, plus the actual cost of the seats them selves. I had my head rebuilt this way, and it cost about 300 buck. but the head works like it's brand new.