Very nice shotgun indeed. I'd recommend that you post on the Shotgun ID subforum of www.shotgunworld.com
. Try to find a camera with a close up macro setting to take pictures of the proof marks, use better light and hold still while shooting them.
I would repeat the comments on not cleaning the gun until you can get advice from someone who knows what they are doing. I would recommend that you get a clean, soft rag (piece of old t-shirt or similar) and put a few drops of gun
oil on it and lightly wipe down the metal parts. You don't need to baptize it, just a light coat of oil will do.
Hoppes no 9 OIL
No 9 bore cleaner) or Breakfree CLP. Any gun store will have them.