Good stuff Vic.
I find it easier to drill the gun port holes after the wing has been joined. If the holes are then accidentally too large, then 'gun port' patches, added after painting the model, and made using the thin tissue which covers many kit decal sheets, hides the error. These are then opened up after painting, using a pin, and 'roughed up' slightly and discoloured, giving the appearance of shot through fabric patches.