I'm not sure what's meant by "don't run an electric pump deadheaded". If the pump is making the desired pressure when the engine is running, it has the same load on it that it would if "deadheaded". Doesn't matter what the engine's fuel demand is. You need a pressure regulator and it will always regulate the pressure to what it's set at. Pumps also have a relief valve built in to protect against true deadheading. As an example, the trusty old Holley "blue" pump is used with a pressure regulator (actually it's a pressure reducing valve with no bypass). But the blue pump has a pressure relief valve built in it.

As for the safety switch, there's another setup you can consider. It's called a "rollover switch", if the car rolls it cuts power to the fuel pump. Some, maybe all, Fox body Mustangs had them. I'm sure many others too, but that's the one I know of.

If it was my car, I'd wire the fuel pump with a relay. The relay would be activated with the ignition switch in cranking and run positions. Using a relay minimizes the electrical load on the switch, and lets you run a 12-14 gauge wire for the pump from the battery to the relay and from the relay to the pump.

I would not run a "hybrid" system with both an electrical and a mechanical pump. Choose one, either a mechanical pump or an electric pump. Do the electric pump installation correctly, with gravity feed. Don't use the stock pickup for an electric pump, as electric pumps don't make much suction. An in tank pump would be the best way to do this for a street driven car, because most of the other solutions have plumbing hanging below the tank which is not good for the street, as it could get damaged (safety again). Don't use the drain fitting in a stock tank as it's only 1/8" pipe, not big enough for a BBC, or a healthy SBC.

On the other hand, there is nothing wrong with a properly operating mechanical pump which uses the stock type pickup. But Tony won't admit there's something wrong with his because he can't/won't find the problem and fix it.