I think you've got the optimum out of a big diameter barrel and a small lock. I like your lock panels, and don't agree that they are poorly sculptured at the back end. If it were mine, I would work on the area at the front end of the lock, to raise the bottom line of the panel to a little more parallel plane, both on the lock and side plate side. And at the front end of the plate, in front of the frizzen, some more sculpturing there would take away the chunkiness there.
1/16" wood along the bottom in front of the trigger guard? How big is the rod hole? I once built a .62 cal rifle around a D weight barrel, and used a 1/2" rod hole on the request of the client, and that rifle was deeper than yours through the lock section. Yet the rifle turned out nicely, and the client was happy. So apart from the bit of work at the forward end of the panel, I think it's fine. Apart from inletting the guard and trigger deeper to straighten out the bottom line of the stock, your rifle is committed. So go ahead and finish it up. Nice work in my estimation.