LD340 and big AVS on the dart
LD340 or the smaller LD4B version on the 318 truck with the small AVS (assuming the PW will be worked hard, towing/hauling). If the PW will not be doing hard work, a 318 2 bbl setup would work fine. If you wanted a little extra hp with some mpg sacrafice you could install a 360 2bbl intake and carb on the 318.

Scott B. "I'm a self-made man... I started with nothing, and I still have most of it!" 68 360 rusty B'cuda 'vert (GO Fish)13.59@ 98.72 mph 69 340 GTS stock 14.18@ 95.60 mph 01 5.9L Ram 1500 Quad Cab 4x4 01 3.5L 300M 16.23@ 86.97 mph