i'm rebuilding the top end of my saphire 4x4 and the head is around some coolant channels realy bad rotten now is my question what is the best i can do about and , maybe a little skim???? what is the standard thicknes of the head? en how much i can skim off i'm using a group A gasket i just look at it and its 1.5mm thick (unused) does somebody now the thicknes of the standard (unused ) headgasket thankx already