cubic inches vs. head flow vs. rpm

Best bang for the buck( talking strictly the motor) is a freshened up R5P7 deal. Easily found under 10k and usually will put out 750-800 horse if it utilizes a roller cam.
Buddy stuck one( flat tappet restrictor plate motor with dinky 248/258 cam) in a 68 Dart and went 9.40’s with it using a 904 behind it. Modified a set of 2 inch W2 headers and built his own front end