My goals for my 65 Dart 273 are about the same - efficiency and smooth running are first priority. I installed a hydraulic cam, the common RV/Torque one, with Rhoads leak-down lifters. "340 TA" ball & cup push-rods (Summit) fit fine. The adjustable rockers make it easy to setup the Rhoads lifters optimally. My eventual plan is to install a Holley Commander 950 for fuel and also control spark timing (via a GM 8-pin HEI) and knock sensor.