Some confusion here. My car is a stock 74 SL Coupe, US model. It only had an electric pump, mounted where my picture shows. Now that is not the OEM Fiat pump. but it is mounted about where the stock pump normally goes. It is wired as Fiat designed. It is wired to two relays that control it by using the oil pressure sensor. Two relays as the pump must be running when the starter is cranking, as soon as oil pressure comes up the main relay powers the pump. No inertial switch. In most accidents the engine would not be running after impact. It is not perfect, but that is how Fiat did it. I would not over think this part as first, you need to fix the hot starting problem. Once you get there, then, if you need an electric pump, then we can help you design the wiring. Yes some pumps are pass through, so you can run an electric pump in line with a momentary switch. The old Facet clicker pump did allow this, I think. When and if you get an electric pump you should be able to blow through the pump. I'd say suck on the output, but I don't want you to ingest any dangerous chemicals. So let us know what happens next.