How to make this Dart Handle?

One of the things you can do to improve handling on any car is to add front and rear anti-sway bars if not already equipped. The sway bars reduce body roll which improves both cornering ability and driver control. If you're going to replace the LCA with aftermarket units, may as well make sure they have bar provisions. Aftermarket and factory front anti-sway bars have different attachment lengths. Make sure that the bar and the LCA will allow for a straight connection. This is essential for proper function.

The only Darts equipped from the factory with a rear bar were the '76 A38 police package cars that mostly went to SoCal law enforcement agencies. The bar on these cars was mounted on the body. After market bars are mounted on the axle. The difference is that all else being equal, the body mount will provide a better ride.

As far as shocks go, recommend just about any major brand gas shock is going to be an improvement over the stock stuff. They also are adequate for a DD. I've used Monroe Gasmatics and Delco Gas Pleasurizers (from Rock Auto) with acceptable results. IMO Bilsteins are the best, but I can't justify the price differential for a DD.