The mechanical pump is by far the best choice. If you do choose to go electric, an oil pressure switch is an absolute must. It has nothing whatsoever to do with fuel injection - - - -it's just common sense to stop the pump from running anytime the engine quits, and an electric pump wired straight to the ignition switch can't do that. I've had good luck with the little inline pumps that look like a metal-housing fuel filter with two wires. There's plenty of them available on Ebay. They don't overpressure and they do deliver enough volume to supply any reasonable amount of demand. To retain the look of original equipment you can gut out a mechanical pump and reinstall it on the engine block with the fuel line running through it. Be sure to put a metal blockoff plate on the block opening and remove the guts of the pump, however.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!