Hi Jaeger,
First, to assure you that I know about what I write here are some examples of New England (very French influenced) and English fowlers I've built.
Your stock still has too much wood left on. It needs to be thinned along the barrel channel and the top edge should be lowered a bit more to expose more of the barrel. We have a saying attributed to Allen Martin, "Remove enough wood until you are scared and then take off a little more."
The flat areas bordering the lock and side plate are too wide. They should be thinned to about 3mm and the shape of the edges should be concave not convex. Thinning them will reduce the need for the big ugly notch for the flint cock. The French often carved the lock panels without much care on these trade guns but they were usually more well defined and smaller than yours. Use half-round and round files, and rounded scrapers to form those edges rather than sandpaper. Look closely at the photos I posted and see how I shaped those areas. You don't see any notches required for the flint cock on my fowlers and they were usually very small or absent on the original guns as well.
dave