Many owners have posted in the past that the gasket maker in the cheese wiz can “The Right Stuff” worked well for them.

I have not used The Right Stuff on the plenum,
but I have used 3 different official Chrysler gaskets on the Magnum V8 thermostat flange,
and finally found that using The Right Stuff there worked MUCH BETTER and was removable.

Other Magnum V8 owners have posted that they TIG welded an custom cut Aluminum plate on instead of the OEM steel plate.

I have a strong feeling that Chrysler should have created a V8 version of the V12 intake manifold. This would improved low rpm towing Torque, improved V8 fuel economy, and eliminated that hidden gasket and the risk that bolts would drop down into the V.