There are several tricks to disguising a Magnum engine as an LA engine. The original look is a great finishing touch to a classic Mopar that has been updated to Magnum power. You probably won’t fool any concourse judges, but the normal observer will never know.
5 bolt LA-style valve covers will bolt onto the Magnum heads. The extra bolt holes in the Magnum heads are simply not used. Unlike LA heads, Magnums have machined valve cover rails, so with decent gaskets, leaks are typically not a problem.
We prefer to use these silicon gaskets, as they last a lifetime, and help stop annoying valve cover leaks. Stock Magnum valve cover gaskets will NOT work with LA valve covers.
This is the most difficult part of the process but also the most important. Having the heads on your Magnum drilled for the LA bolt pattern really classes up the whole swap, and allows for the use of LA intakes as well. Hughes Engines drills heads at a reasonable rate. They also sell pre-drilled heads. Engine Quest CH318B castings are Magnum style heads pre-drilled for LA intakes only. EQ CH318A heads are the same exact heads only drilled with the factory Magnum bolt pattern.
Sourcing some used or aftermarket underdrive V-belt pulleys for your swap helps with the classic look. To use these, you will also need an LA timing cover and water pump.
Obviously, the correct shade of Mopar orange/blue/etc is a must for a convincing LA impersonation. No detail is too small.