My alltime favorite feature on the B16 was the "hand prime" feature on the fuel pump. IIRC, there is a lever on the bottom of the pump which allows you to pump the thing by hand. Handy when you think you might be out of gas and your battery is dead, or your battery is low, you ran out of gas and you don't want to kill the battery pumping gas to the carbs, etc.

It'd at least give you some indication of the conditon of the diaphragm. I'd pull it off take it apart, clean it to get crud out and give it a new lease on life. You could also just test it in the car by disconnecting the inlet/outlet lines and hooking it up to a container of gas to see if if works. It's a little awkward to do this out of the car unless you have a vise or third hand to hold the thing while "pumping".

replace those spacer gaskets and use some gasket sealant, as this seems to be the main source of an oil leak on the engine. Pot metal ears on the pump can 'bend' enough from constant cam pounding to create separation btw pump/spacer/gaskets/block, as a straightedge may reveal.