1973 Dart Sport Improvements

I have a 73 dart sport with a 383/727 setup.The engine is a 1971 model .030 overbore, has a good cam (specs unknown) a good set of 1 7/8 headers, full 3 inch exhause, a weind single plane intake, and a holley 750 dp. The rear axle houses a 3:55 posi. Its been running pretty consistent 13.20's. I am looking to get it down in the low 12's high 11's this year. I have a set of ported 906 heads I am going to install that flow equivalent to edelbrock rpms soon. What do you guys think will help me meet my objective?