Synthetic oil use on flat tappet cam after break in

I saw the benefit of synthetic oil in the late 80s, I was having trouble keeping 4.88 pro gears in my Plymouth more than 125 passes. A buddy said to try synthetic gearlube and I started pulling the ring & pinion at 400 passes just because it seamed like I should. That year I gave up on my Valvoline racing oil ( I still have five 5 gallon buckets of it) and went synthetic in everything.