You are correct on the timing marks, A= Advance, and 0 =TDC.
Using a vacuum gauge to set timing will work. I haven't used it that much yet. I have a 327 that cracked a head and collapsed a piston. I set the timing per the factory manual and it didn't run that well. Having read about setting the timing with a vacuum gauge, I did that, and it ran much better. The down side, and I'm sure this was particular to my motor, it was advanced to the point were it was had to start sometimes. I guess what I'm trying to say is that setting the timing with the vac gauge will account for other problems. Check for pinging while your driving.
I'm sure there will be others chiming in.
Larry
