76 IH 304 started a top end chatter and found an "arresting pin" under ther valve cover and obviousely missing from the "suspected" lifter. I replaced the lifters driver side so far, and found one lifter severely worn on the cam side, almost a 1/2 sphere.(only one). Nevertheless the chatter is still there with new lifters........should I expect a worn cam to replace or maybe worse?? Thanks in advance

Yes the cam is worn also. Thanks to the glorious regulators removing all those fancy additives from the oils.

Swepco 316 like $7 a qt, so just change it half as offen it its breaking the bank

Yes your cam is shit

Just replace the
1. Cam bearings
2. Camshaft
3. Lifters

Edit
About $250 to $300 for the parts iirc

That lifter was installed 90 degrees off. Just turn it back 90 and it will even out.happens all the time.