As I understand the history...
Once upon a time, Jack Garner owned a shop. Jack was thinking of moving into the components side of the business and one of his people, Matt Avance wanted to make guns across town. They came to some sort of arrangement and went their own ways -- each with a variation on the TVM name. As time went on Jack gradually moved back into producing a more guns while still making components. This places them into some degree of competition. (I believe that Jackie Brown was also one of his people and opened up a shop a few miles down the road.) No big deal in my book as I like all of these people.
As to the lock, I have a Siler on my Tennessee small bore caplock and it works well. I use this gun for shooting matches. I am looking at building another one in flint but it will not have a Siler Germanic lock. They were commonly used for reproductions, but there are other options now and I do not believe that it is the correct lock for this gun. I was giving you advice that I plan to take myself.
L&R lock is down the road from where I live now, I like Bill and I am a tad biased toward his products. I like his fowler locks and there are some very good L&R locks out there. On the other hand, I have been hearing good things about the Chambers Late Ketland. When I build my flint rifle, it will have that lock. I plan to make most of my own furniture for that rifle.
As to your time and location, Ghost was on the money. I purchased an early Lancaster kit from Matt and Toni Avance for exactly that reason. I also admire the early Virginia as well. You need to decide if you want the style of rifle or a particular period in history.
Good luck with whatever you get.
YMHS,
CrackStock