The main idea in the stock cooling system is the cap on the tall tank, called the expansion tank, should be rated 2 or 3 psi higher than the cap on the smaller tank, which DeTomaso called the system tank, which you are calling the swirl tank.
Running a higher pressure cap on the system tank always runs the risk of creating a leak somewhere else like the heater core, but if you feel your Pantera's system is up to it, just install a higher rated expansion tank cap at the same time.
-G
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