One of the beloved custom shops picking this up would make the most sense I think, as for price point the difference between a regular 75B and a Stainless one would be a fair indicator of what the price difference would be, maybe a little more for the additional machining of the rail.
As for which one a Shadow or Shadow2. I'd jump on either in stainless. But the S2 being the new kid on the block it would make sense. I have no doubt a stainless would sell like hot cakes and I'm surprised it hasnt already been done with the shadow.
I like matte finish, one of my favorites, it looks great new, but scuffs / holster use show up fast, I'd opt for a Brushed finish, its the easiest to maintain.