I've got a 73 that I've replaced the mechanical fuel pump with an electric one and I'm looking for an easy and effective automatic shutoff for the electric fuel pump incase of a wreck.

My 78 has an oil pressure switch with two prongs on it, one prong goes to the pressure guage and the other one is closed if there is no oil pressure and that shuts off the fuel pump.

Any chance I could just changeout the oil pressure switch for one from a 280 and wire it in?

I know the 280 has a circuit to bypass the switch for starting and the 240 has the carb bowls that would hold enough for starting but I guess I might need some type of momentary pushbutton to run the fuel pump for those times the car has been sitting for several weeks.

Years ago I drove a company Ford Ranger that had an inertia switch that (if I remember right) basically had a magnet and a steel ball that when hit hard enough the ball would drop away and break the connection. It disconnected during regular driving twice

The search engine is your friend. Use "Fuel Pump cutoff" and voila'

http://www.classiczcars.com/forums/search.php?searchid=61685

The pressure switch is the way to go , in my openion. Also install a switch to kill the pump as a security measure.