Most cost effective setup for 65' stang?

yep…install the electronics according to application. There were plenty of salvage late model Mustangs that can be donors for the electronics and driveline

One of the cooler retro Stangs running around here in KC has a complete late model 91 driveline (engine/trans) with electronics, suspension and interior. His dash has been brought up to new technology with led and aftermarket guages to fit the old bezels. It is in a fastback car done up like a Shelby GT350…beautiful car and runs great with all of the modern touches.