The square body Dart continued to 1976. It did not end with the introduction of the Demon in 71, which changed to the Dart Sport in 73. Totally different and separate model.
Use a 400 B Block , stock stroke 3.31 inches. and use trick flow 270 power port heads or indy heads. why Tub when you can fit 275 /60 /15 and people have run 8s on those? use those Cal tracs and E-85
