That looks great. One detail: That mount was used in the B-17G (and many other aircraft) but not in the F.
There was an aluminum shelf that jutted out into the nose:
Mounted to that platform were a couple of brackets with other structure:
And on top of the brackets and structure was this shock mounted plate to which the bombsight (actually the direction stabilizer) was mounted:
Thanks for the great reference!
That's a lot easier to model.