I didn't realized it was a roller cam motor If it is eating a lobe it will have big chunks in the filter, it is a bad roller wheel it would have had a lot more valve to pushrod clearance now
I did a W2 N/A pump gas street motor years ago for 9secondphil, it had a custom ground comp Cams solid flat tappet cam in it with a little over 430 Lbs. opened and around 170 lbs. on the seats, he drove it around 20,000 miles and then the top of the lifter cups started flaking apart sending debris down onto the piston skirts eating them up and the cylinder walls
BTW, did you set your motor up to oil the rockers full time? If not you should That really helps keep the valve spring cool, some guys say that makes the oil temps go up quicker so it must be sucking heat out of the valve springs, huh