Armament options will probably be a one 7.7mm and one 12.7mm gun or two 12.7mm guns in the cowl. I think it could carry two 250kg bombs, but I am not certain of that. It was also the most lightly built of all WWII fighters, so far as I know. No protection of any kind and not as structurally sound as the A6Ms.
On the other hand it should be insanely maneuverable. Take a plane that is already better turning than the A6M2 with a better roll rate and give it fowler flaps like the P-38s and Ki-84 have.