He has what I think is a very nice looking Southern Mt Rifle, .45 flintlock.

Anybody put one together or own one?

I have seen the kit at Friendship and a completed rifle - Current Southern rifle. It is very well done and worth the $. I am still considering one...
I think Jim is also hosting a NMLRA class (multiple days) where one can assemble under his direction.

Yes, I've seen a few clips of that class on Youtube- specifically fitting of the barrel.

The rifle has certainly grabbed my attention; the only downside, if you will,for me is that I much prefer a half-stock.

I only began shooting flintlocks last year but,frankly, I prefer it.

Have you checked his website or contacted him about a previous model that may have been a 1/2 stock?
Also, I'd suggest you make the trek to Friendship. There are many ML for sale by many makers..