Suggestions for my Dart

As is, I would install a set of well ported Edelbrock heads. 1.6 rockers.
Once you know what the heads flow, the cam selection comes down to what speed you cruise at. Select the cams duration based on where that is and have it ground with as much lift as the heads can handle. IMO, a set of 1-3/4 headers should be looked at. 2-1/2 street exhaust or 3 inch for max out put.

The RPM or Stealth intakes are your best bet on making power with a single 4bbl. With a street bound car. The 750 DP will work fine. A larger carb may make a little more power but the slow speed operation may suffer a little.