Jerry, the main difference in the "Magnum" engines vs the older "LA" engines is;
The heads oil like the Chevys. The heads attaching bolts are like Vortecs. Straight up and down. The parts are not able to be directly swapped from head to head.
The heads can be swapped onto a older "LA" engine with some minor creative work. You'll need shorter oil through pushrods and lifters.
Head gaskets are not the same but it will not matter which one you use.
Intakes are limited to a few. Edelbrocks RPM, MoPars M-1 dual or single planes.
Pro-Products Edel, RPM rip off.
The word "Magnum" was attached to big block engines years earlier and have a total of nothing except the spelling of Magnum in common.
A '78 Dodge Magnum has the "LA" engine. Theres tons of parts for "LA". Not so much the body/style /model car. The car was actually designed to be the next style change for the charger. Though the brass of the troubled Chrysler were a tad neverous on a new model intro to the Charger line, they kept the Charger for '78 selling a most undesired amount barley making the 4 digits vs the Magnums 40,000+ units. Thus ended the Cordoba styled Charger very quickly leaving the Magnum name plate for 1 more year.
( Shame it was discontinued after that. )
