I used to work for a machine shop and we had a distributor machine. We would setup street motors, without vacuum advance and set total mechanical advance to fall somewhere in the 30-36 degree BTDC range (24-30 degrees in the distributor with a base timing of anywhere from 6-12 deg. BTDC). By changing advance weights and spring pressures you can set the RPM that the advance starts and the RPM where it's all in. Vacuum advance is only for emissions while cruising (and it does help fuel economy as well). At wide open throttle there is no vacuum being pulled on the vac advance anyway so you really don't need it for power. I don't know what the stock dist. has for total mechanical advance or at what RPM it comes in at, but since the base is 7 deg BTDC, as long as you set it there you should be OK. Unless the mechanical advance is where the problem is.