OK, the idea is not to go the 'arming the V-22' route, which is why I'm shortening the prop-rotors but adding more of them. The idea is to make the equivalent of a Cobra compared to a Huey. For what it's worth, I don't like the AC-130 type of gunship, the Cobra seemed to me to be what a gunship should be so that's what I'm attempting here.
The Gepod is quite a large bit of kit, but here's a comparison of a 1/72 Gepod alongside my sponson. You can see the A-10 GAU-8 barrels and fairing that I removed from the A-10 kit, glued to the front of the sponson (top pic). I've positioned the barrel ends about where it shows in the drawing shown in Greg's posting. The next pic shows the sponsons to the AV-22, which is a big aircraft. As big as an A-10 really ---
The prop-rotor blades are shortened enough that they clear the sponson, although until I get the weapons bay doors done, I think only the inner ones will be able to fire the RP's in a head-on attack.
If you go back to Post #11, you can see how the sponson will be orientated. The bottom half of it has the weapons bay and wheel bay, the top half was to be fuel tanks but I've since changed that. The photo I posted of the barrels/breach and the ammo drum shows some interesting details, it looks like the gun is just bolted down by the brackets it shows. So as the sponson has a mid-point shelf (so to speak) the gun would be bolted down to that.
Sorry, I don't mean to ruffle anyone's feathers, and I know everyone is trying to offer helpful advice, but the plan is to make a modern day Cobra.