When you connect a gauge to the port on the flow divider you should only have high pressure when the wheels are turned to the max right or left turn.  I would try to get the #'s from the Char-Linn unit to check if it is for an open center system. The max. steering pressure should be 3 to 4 hundred PSI below the main relief pressure setting. It appears to me that you are blowing the main relief because the flow divider is trying to supply a blocked circuit. You will damage the pump quickly if the problem is not corrected quickly. Do you have an Oliver Shop Manual? 
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My Ph# is five seven four-two four three-five seven one if you want to call.