Jeez, you know I hate to have to report that something is being redone, and that's why it's delayed - but that was exactly the case with the prototype RN Twin-6"50cal MkXXI Turret; under development in 1/550 scale for this build (and subsequently for commercial release). I discovered my design to permit elevating gun barrels was not compatible with any accurately-shaped turret face - which in fact may well explain the substantial innacuracy of the original Airfix turrets, as well.
In any case, effort on the build is currently focused on redesign and reconstruction of the master:
Click on Image to Enlarge
And another development: notice how much narrower is the barbette on the Airfix kit (left) than the turret master; in the real thing (right), note the barbettes were fully as wide as the overlying turrets. The prototype, at 1/550 scale, should be 9% wider than a 1/600 scale barbette - or 10.4% larger than on this Airfix kit, which was found actually be 1/607 scale. However the difference appears clearly to be twice that - or more; proving that these Airfix barbettes are 'way undersized, even for its own scale. Thus, a decently-fitting barbette master will also be developed, to accompany this turret.
Meantime, in the picture at left note how much the painted deck looks like real wood, if not exactly like planking - though there may be something(s) more I can do about that, given the underlying Airfix deck still has a nice, scribed planking texture.
Will keep you posted...