Old Benjamin 392P

Okay so I recently found my dad's old Benjamin 392P which he tried repairing, but he passed away 2 years ago. So after looking at diagrams(which didn't help because it was diagrams of the newer 1995 and up 392 air rifle). So I kept tinkering with the trigger system and got it working. Now I found the pump mechanism(the plunger thing) and it is kinda worn. Now I know my dad tried operating on the air valve on the gun, but he never finished it.
After research, I found out that I the air rifle has a soldered air valve and the newer replacement parts will not work for it.

So I am asking your help if anyone knows any sites that sells parts or the special tool to gut out the air valve. I am aware of the rebuild kits for the Pre-1995 Benjamin/Sheridan, which I am considering to get, but I just need your take on what else I might need.

Pics to be posted soon, but its a semi-restoration project I guess? The rifle seems to be pre-1995 so its an old fella. But from the looks of the mechanisms, it seems to be functional. It just doesn't hold air which I'm assuming is just a simple gasket/oring replacement. Hopefully if it does get fixed, I will not put any petroleum based lubes anymore on my rifles, haha, I need his thing to last. It has so much character.