@Rainy Day Auto did a post a few weeks back talking about 360 external balance Flywheels for 4 speeds. Someone had a picture for machining a flywheel to fit a 360 external balanced crank. Probably different than what you need for a Magnum 360
Yeah, Magnum is a different balance than LA360. Plus if you're going to run the factory EFI the flywheel needs the 8 pickups on the back side of the flywheel for the crank sensor.