Actually, I’d just hit the American fleet in it’s infancy (at least knock out that BB) and then return to Japan with the remnants. After all, you don’t actually need 1 AC and 2 BBs for Japan once you’ve decimated the American navy. You might even want to consider sacrificing the ships against the British fleet and follow it up with a luftwaffe attack to resink the British fleet.
Japan’s in the best position to rebuild a navy anyway. It’ll take America 3 rounds to attack her by sea. (1 round to build, 2 rounds to move) and there’s no way they’re going to do it in two rounds anyway, since they absolutely must build enough to take Japan and, as Japan, you’ll have plenty of time to put a few subs in the water to stop that.
So basically, the choice is, retreat into the Pac to support it and stop America from thinking about it or follow through after Pearl and try and hit the British fleet once.
It’s almost a non-issue if you play 2H BBs since you’ll get 4 BB shots at the british fleet, more then enough to cripple it. It’s a bigger question when you have to wonder if the Brits/Americans will sink them with their fighters before you get there.