Converting Walther Dominator 1250 to Walther RM8?

I have a Walther Dominator 1250 I purchased a couple of years ago during that crazy blowout Umarex USA had. Love the gun, though I had a couple of issues with it and ended up with a really sour taste in my mouth after dealing with Umarex USA.

When I received the gun back from Umarex USA, they replaced my barreled action with one from a Umarex 850M2. Now the fitment of the two stock pieces is poor and I've grown to really dislike the stock.

My plan is to take my 1250/850M2 hybrid and drop it in to a Walther RM8 Varmint stock along with a Best Fittings Carbon Fiber bottle. I'm assuming the footprint of the 1250/850 M2 is identical to the that of the RM8, so it should be a direct drop in? Looks like I'd be able to use the factory regulator, just need an inlet valve for the bottle?

Seems like it would be a fairly straight forward conversion, but I want to make sure I'm not overlooking anything before I proceed.