I filled and sanded down the shims and putty in the gaps, and now it looks pretty decent.
I also added a bit of plastic rod in the wheel wells to act like a part of the gun barrels.
Just need some gun metal on them to look the part.
Still need to do some touching up on the seams on the underside and perhaps on the wing joints too. A lot of detail gone though, but not sure how to get it back or if I just should leave it be.