You can advance the timing all day and get more vacuum, to a point.
Vacuum does not dictate where the initial needs to be,idle maybe, I've never done it that way, don't know anyone that does.
I advance the initial till the starter kicks back then [fully warmed up] then back it off 2*, thats where the initial wants to be. Then you just play with total timing settings till you find what it like and BAM you have you're initial/total figured out and just need to limit/taylor the curve to have the initial you want and only advance to the total timing you want.
All my cars are really fast, people always say DAM thats fast for a ?? size motor.
Try it sometime, you'll be pleasantly surprised.