You have a very fine watch recased in a decent carry case.
The watch is a keyless fusee. These are very high grade and rare. I suspect the AD. G. maz is a kind of caode for a date. The most famous is Charles Frodsham's AD Fmsz which is believed to stand for 1850 and it designates higher grade items.
Your watch probably had an 18K case.
Recasing is a contentious issue, I think it sis better than leaving the movement basre.
One possible problem you may have is the watch not running well in the pocket. The problem is that a keyless fusee has needs a special clutch to disengage the winding crown when not being wound. Keyless fusees need this because the normal arrangement results in the crown turning as thet watch winds down. Sometimes the crown can catch a thread abnsd wind on it and stop the watch.
This is unlikely, but this mechanismis very difficult to re-install in an American watch case. IT has probably been lost in teh recaing.
Nevertheless a keyless fusee with updaown indicator is pretty near the top of the heap watch wise.
The movement is very likely English.
The "notch" near the screw in the balance cock is a wear mark from the waatch movement that was in the case before this one.