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hylomar is also what is suggested by some for the metal headgaskets.
It comes in spray cans, and also little glass bottles with a brush. Oddly, its easy to find here in Oz, unlike the majority of other useful sealants/fluids/additives talked about on Rennlist
Dunno why not all studs, but GB does 6 or 7 studs just across the front. Perhaps there are other holes near the oil pressure sender, etc. that are more convenient if there's a stud there?