Timing help please

With that cam anywhere from 16-22 initial is the norm.

Limit the mechanical in the distributor to hit your total number.

600 rpm is pretty low for an idle speed in gear. I bet it currently drops a couple, maybe 300 RPM, from in neutral to drive.

Get the initial up, reset the idle speed and mix screws, then judge whether you need a different PV. The increase in initial from 10*, will pick up your vacuum reading.