Not sure about the TB from the Caddy, but something to think about before going the FI route. You'll need a high pressure pump and thus a fuel return line to the tanks.
What aspect of the Edelbrock 750 was lacking, economy, power, responsiveness? There are metering rod kits etc that are available for that carb. I know they are set up to run on a 300-350 hp SBC out of the box, so I'm sure there are adjustments that need to be made in order to taylor the carb to your application.
Just a thought,