I have owned many of these, and yes, its a common issue. im sending along a link to a discussion about this subject, and I will post up here (copy and paste) what someone wrote thats pretty worthy. Good luck !
there is some deposits around two of the exhaust valves and one of the prechambers that can be seen in the picture...im not quite sure what that is, hopefully not water scale...i dont know if the engine was overheated or had a blown head gasket before i got it...any help would be appreciated!!!
www.dieselplace.com
"Check for cracks on both heads but they are common to crack between the valves. I have reused those heads with cracks between the valve area and never had any issue.It would not hurt to have the cylinder head mating surface machined just a little.Maybe .005" or so which is'nt much.Check your block as well on the deck area.A removal of .005" there wouldn't be a bad idea either.Ive had both of my olds engines machined on the deck area.Having .004-.007 removed with no issue.You just need to use the .010 thicker victor reinz head gasket."