Thanks Wurger! That's exactly what I was looking for.
The Gun pack that comes with the kit is the "b" type, where the Coastal Command Mk IV carried the "a" type.
From what I can see and perhaps conclude is that both have the same dimensions, but that the "b" type has an extra "box" attached" so the guns sit lower. I think I can scratch build the "a" type, using the "b" as a guide.
edit:
I came to the conclusion I can make an "a" type from the "b" type gun pack by cutting off the extra "box". I'd just have to make new mounts for the barrels of the guns and add some detail.
The gunpack was cut down and wet sanded on the fuselage in order to get a correct fit. The resin part itself had a flat base, where the fuselage is not flat. Therefor this was the best method to get a fitting shape for this part.
I assume the pilot had a gun sight for the gun pack that was mounted on on the nose?
I also started painting the cockpit and turret parts yesterday. Starting with a dark grey base coat, followed by some interior green.
This is just the base, still a bit too dark for RAF interior green. But I'm working on that.
I'm amazed by just how detailed the cockpit parts are. These are among Classic Airframes best I've seen so far.
I also took a second good look at the turret and the fuselage surroundings and it looks I'm in for a bit of extra work there. But looking over the kits parts again, I think it can be done with minor surgery, or at least I hope so...
The parts need some extra detail, but it's a start. I guess I can modify the kit part and scallop it as per reference.
pics are a bit over saturated, but it's the only way to show the details of the wheel bay