ToTW. Chambers, Pecatonic, TVM, MBS, all have nice kits. But a note of caution.
I've two examples from ToTW where I ordered a stock pre-inlet for the barrel and lock. The lock placement was too far back by 1/4" to 3/8", which means I would be drilling the touchole into the breech plug. I caught the first one and made an adjustment in the barrel placement, I sadly missed the second one, and had to do some extensive work on the barrel. Moving the lock placement too far foward means a hard trigger pull.
Typically the barrel is inletted first, then the lock location is determined by the face of the breech plug and inletting begins. If the lock is pre-inletted, You can move the barrel backwards in the stock, but it leaves a strange looking area at the top of the lock.