help 69 dart suspension set up

real good set of shocks, lightening the front end as much as possible (aluminum intake manifold/ heads / waterpump / AC delete / headers can also cut some weight), moving battery to trunk, widest tires you can fit without rubbing (taller tires will slow you down however, more rotating weight), you want disc brakes, for sure. aluminim wheels instead of steel.

a lot of it depends on how much money you can put into it. hotchkis has a lot of stuff that can help, the cost is not too exorbitant.
http://www.hotchkis.net/search.html?Make=13&Model=1351&SubmitForm=Search

i think the RMS front kits are cheaper than magnumforce but they do cost thousands and they also get you with the options.