allmost all the original pistons have kissing marks on them not to worry...
throw away the stehbolzen and use the ORIGINAL ford head bolts, these seem to work better....
(and a lot easier to get the head off next time
only problem with using these is there are no locater dowels for the head in the block, so be carefull when installing the head.
i had problems with the post motorsport head studs, now with the normal ford bolts, i haven't had a problem yet