Magnum engine in an A-body?

For performance, I would look at what the Dakota R/T guys are doing. If you put a 96 or 97 and later setup in your car, you should be able to duplicate what they are doing and get plenty of performance.

I would recommend you run an auto, if you hadn't already planned to. The problem with swapping one of these motors in a car and retrofitting the OEM injection is it needs to see a crank position signal, and Mopar did that with a tone wheel in the bell housing. If you run an auto, you can just notch the bellhousing for the sensor, and run the factory flexplate (after slotting one hole). With a manual, it becomes really difficult to find a way to provide that signal as you have to swap to a truck 143T flywheel. I've been working on building a pickup that mounts to the end of the cam, but it's a long ways from even trying it.

If you have some change in your pocket, the best way might be to pick up Mopar Performance's kit that swaps the 390hp 360 crate motor to EFI (google "P5153590"). Take a look at the Mopar Action Savvy Savoy for how that all works. It would still require you to duplicate the 390hp crate motor, though as I don't think you can buy them anymore. Not even sure if the kits are available, I know the pushrods for the magnum head conversion are discontinued.