you could always look into a electric oil psi sending unit, like a autometer or something like that. Hook it up and see what happens and compare its readings to a mechanical gauge hooked up for validation purposes. I have no clue if that would work or not, I'm not sure if the factory dash gauge will function with a different sender. That would probably be the cheapest way but who knows if it will work. I've never used anything other than a mechanical oil psi gauges.