Sorry for the late post, but I have used the DO0E head several times with good sucess. They do need some help though. There is an EGR bump in the exhaust that needs to be smoothed out to flow properly. It is relatively easy
and with a good die grinder, a fairly quick job. Don't worry about an exhaust hole that some of these heads have in the exhaust port, it will probably plug with carbon. If there are external EGR holes, pipe plug them and forget. I used these heads without hardened seats (unleaded gas !!) and had no problem. Usually a good valve job and knurling the guides will work if they are close to max wear tolerance. If too badly worn. either bronze (which I question the use of) or machining and replacing with new cast steel pieces. Pull the rocker arm studs and tap for screw in replacements - also an easy job. Just make sure you have a new and sharp taper and plug 7/16 tap - don't need the bottoming tap usually. Just clean up any casting flash around the intake and exhaust ports - don't port unless you have a flow bench. A new set of rockers, original rail type, or better yet, rollers will complete the job. You do need to check for cracks and levelness. (My last set of untouched heads just went to the dump???? )