While all F6F-5s were able to accept two 20 mms and four 0.5ins this setup was hardly ever used in RL. I can't recall ever reading of an instance of it being employed outside of the F6F-5N night fighter. That aircraft also had a heavy and draggy radar installation under one wing, so realistically if you use the existence of the F6F-5N to justify the cannons you'd have to have the radar as well.