Vacuum advance on 318

The higher the quality fuel I run the more I ca advance correct?

I usually run a 98 octane..

Yes, but only run what you have to run to prevent detonation. You`ll get more power from a lower octane gas. The timing is something you can experiment with. Try to find the spot where you get proper performance without detonation. A 318 2 barrel engine is a low compression engine and should run well and without detonation on regular gas with moderate advances in timing, for example 5* BTDC.