I think the Allies can throw everything they have at Afr and the Italian fleet early with the intiention to kill the fleet and cripple Italy by rd 4. After this the US has the freedom to confront Japan in the Pac if it wishes or just continue and try to actually take Rome or Berlin.
One caveat though: if Japan deploys its fleet aggressively vs. the West Coast, you really can’t wait since once your Pacific fleet is sunk it’s almost impossible to rebuild. You’ll be forced to build at least enough to defend yourself vs. a Jap carrier strike, but that doesn’t mean the basic strategy changes. You need a carrier and some auxiliary ships afloat off the West coast as a kernel of your Pacific fleet to have any chance of challenging Japan. (All this assuming abandoning the Pacific ocean is not your strategy.)