Twin Wildcat - say, Grumman dumps F5F XF-50 and builds this plane.
Users: USMC, USN, RAAF, RNZAF, RAF, mainly in Asia/Pacific. Wing power loading more favorable than Hellcat Corsair, so we hang a torpedo under inner wing. Night fighter-ready. Speed now on par with latest Zeros, greater if we mate two FMs. At 1st, historical undercarriage, later replaced with single unit per hull, hydraulically operated. Fuel tanks in outer wings.
Now, we bolt on 1700, and then 1900HP R-2600s for 400 MPH+