Humm, they thought 14 guns was enough on the B-25H but this was still designed though as far as I know not used in combat. It was designed by Paul Gunn with a 3 gun modification. Feedback from that allowed NAA to develop the Hatch gun as part of the strafer program. Designed a 325 lb hatch blister that was installed directly into the forward access hatch opening using the same pins that retained the hatch door. Only draw back was now the rear hatch had to be used to get into the aircraft.
Now that's interesting, off hand I have no idea what that is up there. Looks like a barrel but the 75mm cannon down by shark mouth and that looks bigger. I wonder if that's a field modified for a camera for damage assessment.
Here you go Snautzer, found what that big glass was on the upper nose piece. Read the info in picture from squadron signal book walk around on the B-25