You could also go with 2x 6oz on the bottom or maybe a six and a 10 oz on the deck. Don’t wring the resin out of the glass so much. A little extra weight in a longboard is a good thing, helps with the glide.
sometimes Mitch’s will have a classic weight blank in the shop that someone ordered custom, but didn’t pick up because, e.g. they ordered natural rocker instead of Frye rocker. “orphan” blank = Heavier board w/ no delay.
Usually the wait for a custom blank is not too bad, just order the classic foam and wait a while, instead of adding extra resin or something along those lines. Extra weight = stronger board.