Magnum vs LA block...differences...preferences

Magnum engines were also made with tighter tolerances and more accurate machining. The factory EFI also pretty much eliminated cylinder bore wear; it's rare to find a Magnum engine to not have cross-hatching left over in the cylinders regardless of the miles. Check out Magnumswaps.com it's pretty commonplace for people to take junkyard Magnum short blocks and just build those up, little to no machining is usually required and with proper heads and thin head gaskets you can get 9.5:1 compression out of them.