Been away. But if i remember correctly I had an issue with the original 2 stage pump, it failed and the replacement didn't work either in supplying fuel. That was back in the 70's when i got the car from my Grandfather. I installed an electric fuel pump, now i have a rotary 6v unit mounted back by the tank with a canister fuel filter from Summit Racing. Don't remember if i thought the cam lobe went flat or what, been such a long time. Of course the mileage was low as it was only driven in town and my GP was "thrifty
I have made a bracket where the original pump was and installed a pressure regulator there, then a check valve right before the carburetor and she starts quickly.
Still have to ponder what to do, I don't drive it in the rain. Is there a good way to test the 2 stage pump to see if the vacuum portion is working?