ALERT!! SOUND THE ALARM!!..

I don’t think the LA based aluminum heads changed, if I understood that correctly. The Magnum heads are the different ones. Chrysler changed the coolant pages when the Magnum heads came out, then EQ kept that for their replacements.
The Cometic gasket likely has a raised embossed sealing ring around the coolant ports. That would make sense why the LA gaskets may not seal, because the smaller raised area would fall into that bigger triangle passage on the Magnum.