Ron,
I have never done this before myself, but I have had a couple of heads worked on and always had the valve guides redone.
On the 292 head I had done a while back, the valve guides were knurled to improve tolerance, but the spark plugs also had covers on them to reduce oil fouling. My guess is that the guides were worn so bad that the exhaust resembled an insect fogger.
I don't know if they were bored out and new guides pressed in or ???
I do know that the new guides that were pressed in are an alloy that resists wear and oil migration better than the original guide material.
Another important factor when you are getting your head done is to make sure that you get hardened valve seats - AND - tell them you want the seats to be at stock heights. Some shops sink the seats deeper and this kills flow when the valve is open as well as then requires spacers under the valve springs to get proper compressed height.
You get what you pay for and a good and thorough head rebuild will cost a few bucks.
