I don't know what the silver fitting in the fwd port (for rear brakes) is. Some MC's had a "residual valve" in a port for the drum brakes, but I don't think it sticks out and is visible, and wasn't used by the 1980's. Your ports look like the smallest tube nut size for 3/16" tubing. The threads are standard SAE, so try screwing different bolts until you find the thread size, then compare to tube nuts, or take it into Ace Hardware and use their "thread finder" tool. I recall many sellers on ebay list the thread sizes. You will need a "double-flare" tool to make the tubing, and don't skimp on a cheap one or you will get frustrated. Many here like special tubing (Ni-Cu I recall) which is much easier to bend and flare.
