Ouch!
Keith,
this has been a problem for a few years now, there are several possible causes;
>>bronze gear
>>iron gear used with steel roller cam
>>high volume oil pump (some cam manufacturers make this claim)
>>no ZDDP in the motor oil
>>bad camshaft core
>>mis-alignment of parts
Dan Jones has a very long treatise on the subject you may be able to find if you search this forum.
To do your investment in this motor justice, it should be pulled & torn down, every passage inspected and cleaned, all the bearings inspected, the pan thoroughly cleaned, the oil pump especially taken apart & cleaned.
I feel for you my freind,
George
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