Greg, I have a Parker VH 12ga, 30" on a #2 frame. It's been totally redone: restocked to modern dimensions, reblue and re-CC, custom engraved, etc. It also has a set of Briley thinwalls. I didn't do any of that to the gun, but the result is a very versatile sxs target gun. I can shoot skeet, trap, sporting clays, whatever.
That being said, I don't think I'd do that to a nice Brit game gun strictly for field use. A Brit fowler or pigeon gun, to make it into a versatile target gun . . . maybe so. But I'd probably look for something the British equivalent of my Parker. In other words, a pretty basic Birmingham BLNE.
