This would be a relatively quick and easy add. The F4F-4 with the 4-gun option IS NOT an F4F-3. It's an FM-1 (license-built version of the -4 which removed the outer guns, but was otherwise the same aircraft). The F4F-3 lacked folding wings and was lighter than the -4, giving it much improved handling characteristics, a higher top speed, and greater rate of climb. Navy and Marine pilots preferred the -3 over the -4 both because of the superior performance.