Another quirk of the 265's was the distributor. It had a flat spot machined in the housing that allowed oil to get past the distributor and fill the valve lifter galleries. If the distributor was installed in the wrong position and the plug wires were walked around the cap to compensate, the housing would cut off oil flow to one bank of lifters. Later model distributors had a full-circle groove instead of a flat spot on the housing.
Jerry
In high school & college breaks I worked for a guy with a small shop in a town of 180.
He bought an old boring bar, built a hot tank & quit sending that work to the machine shop 60 miles away.
I installed the o.e. now .030 over 265 into `56 pu & no oil to the rockers!
Ground flat on new cam to match the original.
