Hard anodized and inconel exhaust valves are a must too.
I just freshened up my heads, with the exception of a valve spring change in 2008, and all that needed to be done was exhaust guides, seals and a valve job. I chose to replace the Isky Tool Room springs while I had them apart. So, longevity is looking pretty good. As for the Crane roller lifters, 31 were still good! 1 was on it's way out. So lesson learned...250 hours, replace the litters too!