After you've installed new spark plugs and a PerTronix Ignitor, the ignition timing needs to be set properly. Adjust it for total advance, not necessarily timing at idle. With the vacuum advance working, rev the engine to 3,500 rpm and hold it there. Total timing should be 36 degrees BTDC. That's exactly 2 inches to the right of TDC on your small-block Ford balancer. Mark it or use timing tape to get it accurate.