i wouldn't be put of using a bead of silicon on the china walls, even most 'rebuild' books suggest using it instead of the cork gaskets and they're written by smarter folks than most of us :thumbsup: . if the cork sheet you have isn't thick enough to compress properly it will leak. even the stock thick cork seals compress a surprising amount, have you tried a dry build to see if they compress enough for the intake to seat correctly at the heads?
neil.