Where else do I look for numbers/proof marks? Do I need to disassemble the gun to find them?

You are correct, no scope at all. Just the gun as you see it.

The numbers seen in the 3rd pic down (where the gun is cracked open) are 19207.

All the other numbers/proof marks shown further down in the pics were found under the barrel stock (geez, I hope that's what it's called. Where else on the gun would numbers/proof marks be?

Here is a better pic of the marks shown above...you can see them in one pic here: