how many miles on this thing? Replace all of the rockers. Also replace the cam shaft bearings i'm guessing they are around 25-30 bucks each and you will need 3. It would be best to do a head gasket if it has high miles and get the head resurfaced and if ya had an extra 100 i would do atiming chain assuming there are high miles. 
About 145000 mileage on the rig.
I dont know what else has been done, but I think the timing chain has been replaced not too long ago... and generally the thing has been maintained fairly well over the years.
