Thanks everyone for the replies... I've been gone Quail hunting and just got back to see these last posts! I hadn't thought of the sideplate as a repair, but now that it's been pointed out, that most assuredly is the case. I don't have any reason to remove it to see what's underneath..., it's a really good fit even if it has too many screws in it.
I am posting pix of the tang inlet. Also, the top of the stock is flat, and I thought that might be of some help. Finally, the barrel was pinned and not wedged.
Also, the owner of the gun was from Ohio..., I received another longrifle from the same person. That gun was in many pieces and ready for the trash bin (it's at least a good looking wall hanger now).
Both rifles are .36 cal.
On further sleuthing, I found "serial #'s" elswhere...., there is a number 13 stamped in the stock (under the barrel), on the inside of the lock plate, on the trigger assembly, and on the trigger guard. My original post showed "Remington" and "1.3" on the barrel...., it must simply be "13" as well. That tells me that all the pieces are original and related.