Ok, I have filled the gap with epoxy putty, it was pretty straight forward in the end, and the bigger opening made it easy to get to the inside of the front bulkhead.
Now for the fun part.... as you can see the bottom and top hulls to meet flush. There is a flange running along the top hull but its no use to me if the bottom hull is too wide. I will have to pull eash side of the bottom hull in just enough and fix it to the pressure hull. There will still be a gap between the pressure hull and lower hull that will need to be filled even after I have pulled it in.
