Re: pistol grip stock?
If I were you I'd simply invest in a couple of long distance telephone calls to makers of aftermarket "tactical" stocks and ask them if their products can be made to fit your gun.
Most of the popular pistol grip stocks are advertised for the Remington 870 or 1100, the Mossberg 500/590, the Winnie 1300, and ocassionally for the Ithaca 37 -- as you may already know. None of those are configed like a side-by-side. But that doesn't mean one of these items couldn't be adapted to fit yours. It's worth a call. I'm also guessing there's at least one maker of custom wood stocks who'd carve you one for a price.
The Second Amendment does not exist
to protect the gun rights you like.
It exists to protect the gun rights you hate.