There is normally no screw holding the front of the trigger plate on a Southern rifle including the makers you mentioned. The trigger guard held the trigger plate in at the front and a wood screw held the trigger plate at the rear, behind the rear trigger spring. I cut off the front of the trigger plates and notch my trigger guards to allow the trigger plate to remain flush with the bottom line of the stock and also allow the front extension of the guard to be inlet flush with the wood of the forearm. Trigger plates should always be flush with the bottom line of the stock. If an original wasn't that way, most likely, the maker was just being sloppy. Also, the trigger guards on iron mounted SW VA and E TN rifles were almost always attached with a single wood screw in each of the front and rear extensions of the trigger guard. I have rarely seen one pinned, and if it was, it was the front extension. This is because the front screw will hit the barrel and must be particularly short with the threads going all the way to the guard. I have to make these screws. Pinning would be a better solution but it was rarely done. I would save that for a particularly fancy iron mounted rifle. I have considered installing a tab and pinning the front extension on my personal chunk gun. Given that it is filed up like a brass guard, it would probably look better.
Southern rifles (at least from SW VA south, and certainly E. TNs) almost universally had wood screws hold the tang of the breech plug. There was no tang screw going through to the trigger plate.
If you inlet the front of the trigger plate too deep, you can put an adjustment into your trigger bar position by putting a flat head wood screw into the mortice over the front of the trigger plate. You will need to screw the wood screw almost all the way into the wood so that the flat head of the screw is just a hair above the wood in the mortice. This will hold the trigger bar a hair off the sear and serve to resist the trigger moving in relation to the sear as the wood compresses under the trigger plate and the stock shrinks. You can, of course, adjust the screw.
I also put a screw through the trigger plate under the terminal end of the rear trigger spring. This serves as a stop to take pressure off the sear if you can't give as much clearance as you would like between rear trigger bar and the sear. This screw usually falls in the little space between the bow spur and the grip rail of the trigger guard. You will see such a screw on some original rifles.
I also frequently bend the sear up on very thin Southern rifles. On the thin Southern rifles that use the relatively large Chambers Late Ketland, there is no way to properly fit set triggers without bending up the sear a considerable amount. You just can't take enough off the trigger bars to compensate. Sometimes, I have to bend up sear, grind down the trigger bars, and install a stop on the rear trigger spring.
By the way, the sear must be bent hot and several tries will probably be necessary to get the sear bar positioned exactly where it needs to be. Once everything fits, you will need to re-heat treat the sear.
