Dart 4x4?

If it was me (I'm going with a slightly different route, turning my '65 Fornula S Barracuda into an AWD). I would order 2x3 or 2x4" bulk rectangle tubing from Summit (in their Chassis section) and fabricate a new frame, front to back that followed the contours of the A-Body rails.

Go with a 8-3/4" Based Independent Suspension Front, with Tubular Control Arms and early (87-90) Dakota Spindles, Rack & Pinion from a early 00's Dakota, and an 8-3/4" Rear or go independent in the rear aswell. Top it off with an AWD Transfer Case from a late 90's Dakota behind the Auto or Manual of your choice.

Some of that is based off of what I'm doing with my Barracuda, only I'm tying the rails together with subframe connectors and doing a cage, and it won't sit as high as the Green Dart that Ddaddy posted (though that thing is cool, I'd drive it everywhere!)