'68 318 to carbed Magnum 5.2: Check my checklist

You actually have me confused on no oil to the drivers side.
Mags oil thru the push rods to the rockers.
The lifters have to be defective.
Spun cam bearing would loose oil pressure to the whole engine, and the passenger side would have no oil also.
Here is a pic of a new roller for a mag, I assume yours look like these?