Buck,
Good to see that you now know who built your rifle.
Well done Axel for identifying the maker.

The action on this rifle is similar to what is often seen on Belgian double rifles.
There are a couple of small differences though.

The slot in the breech face which accommodates the barrel extension is milled right through to the top lever.
This slot usually terminates just before the top lever.

There is a drilled hole high in the breech face which is not common in Belgian DR's that I have seen.

Striker bushing keeper screws appear to be brass. These are usually steel so may not be original.

Barrel extension appears in the photos to be two piece, where dovetail lump guns would usually have an extension made from one piece.

The top lever screw usually/often would have a small keeper screw.

It should be a nice gun if everything works ok. There might be a few little problems to start with but most can usually be sorted out without too much drama.

Looking forward to hearing how it shoots.

Oh by the way, if you end up taking the action apart for work or cleaning etc, be aware that the cocking lever screws sometimes have concealed keeper screws hidden under the action bottom plate.