efi or carb
My buddy just had the RB unit fitted on his '69 440 Coronet. It's been absolutely flawless from the install, and transformed the start-up, warm up and daily driving manners of the car.
I would look into the Holley retrofit stuff first, but the 5.9 Magnums come with all the sensors in place, which makes it a lot easier. If your not afraid of a little wiring, you can have a very nice state of the art system.
EFI and overdrive are the two best add-ons you can do to our old cars.