There is a feedblock on Ebay right now
Its an aftermarket powerfeed, and the seller is asking way too much.... but if anything, its good to know that you can find parts like that.
Looking in the BST, I see a feedblock for $4. Even with international shipping, thats a pretty good deal.
That might be gone, but post something in the WTB. I'm sure you get something.
Anyway, that gun looks pretty much 100% complete. Usually the thing that goes missing is the thumb-screws, but looks like they are all there expect for the 2 on the feedblock. Those actually might be very tough to find at your local hardware store.
Otherwise, looks nice.
Are you asking where to fill that 3.5oz co2 tank? Same place as your 7oz, 12oz and 20oz. Its just a normal size tank, though you do not want to use that tank by itself. You might only get 40 shots... YOu were supposed to use that tank along with a larger tank on the backbottle, using both at the same time.
There was a BRIEF trend in the early/mid 90s for guns that could run dual tanks. But it was tricky if the tanks did not have on/off valves. Not impossible, just an extra thing to worry about before the game starts...