Pretty interesting! I don't think it's any earlier than the 1790s at earliest and it may be first decade of 19th century. Everything is fully-evolved here. Also if I may say so, I strongly suspect more has been done to the lock than simply a replacement cock, but nevertheless the plate fits very well and likely we're looking at the original lock plate at least.
That V-shaped forearm (as opposed to fore end) seems to me to be less of a regional thing and more of a quirk-of-the-maker thing. I've occasionally seen that on rifles from a very wide variety of areas. Most Bucks and Lehigh guns have the V-shaped fore end but a very squat, well-rounded forearm. At least, most that I've looked at anyway.
Overall the condition here is fantastic.
