Being a flinter, I doubt that you’ll have much trouble, just watch out for how TOTW gets the lock mortise laid out in relation to the breach of the barrel and any inletting that affects the trigger and side plate in relation to that lock placement. Look these things over real well before you start doing anything, a change that you make for one thing can cause issues for other down the build. That’s why some will knock pre carved stocks, cause not everything is done as well as we’d like. I’ve never built any of these, but have built plenty of other ones from them. Personally I’d see about getting a stock that isnt inletted for a lock if possible. I’m not sure if they thread the stud on the guard, but that isn’t hard to do. Good luck on it.
Bob