yes, I have also modified fuel pumps. As long as they have an inner seal where they wont dump fuel into the crankcase, you drill the slotted vent on the side and run a tap in there and thread in a small piece of copper or brass pipe. I lucked out by cannibalizing an old torch that had the perfect bronze tube. Ran a 5/16 die on the tube and a 5/16 tap in the pump. made a very nice fitting for to run the clear line up to the carb.
Look into the open end where the arm is, on mine, way down in there, you could see the seal for the diaphragm pump rod.
You want your new vent to sit on top of the diaphragm so if the diaphragm rips, fuel sort of is sucked-pumped up to the carb, makes the engine run rich and the clear line shows a pump failure. You don't want a vacuum on this line, it might affect the pump action. Diaphragm has to move freely to pump fuel.