You just made one of my dream guns!
How much did the barrel cost to have made? The SRH is the perfect platform for this, because the barrels are just round with no contour, and if you have a scope mounted you don't need a front sight. It would be MUCH harder with something like a GP100, Redhawk etc, because you have to mill in the ejector rod cutout, etc.
It is perfectly legal, you can buy kits to convert a 1911 pistol to a carbine with a 16" barrel and a stock........you just have to install the barrel first, and then the stock. You can have a pistol with as long as barrel as you want, but you cannot stock a modern pistol with a barrel shorter than 16", with the exception of some C&R pistols like Mauser Broomhandles, Hi-Powers etc.
It makes perfect sense to me, I'm a revolver nut and I have always dreamed of a revolving rifle based on a modern gun, like the Super Redhawk. I would use a .44 Magnum because then I can actually afford to shoot it
If you have the $$$ any custom stockmaker can make you a stock, in fact it would be easy since the SRH uses a grip peg and all you gotta do is make a stock that fits the peg. It would be harder with a gun with a grip frame like a S&W or a Redhawk.