high oil pressure 85+psi

[69GTO]

I recently just over hauled a 20R and we have run into a series of problems the oil pressure is being the biggest one at the moment. we have blown out three oil filter gaskets. put a gauge on there to see what it says and its at 85+ psi just off of the starter we have removed the plunger for oil pressure relief valve and moves freely the gasket surface where the filter goes was fine the oil wt is 10-30 not sure what else to say but I am at wits end right now. Ideas thoughts divine revelations etc.