In simplistic terms you want a cam that makes power to about 5700-6000 with a broad torque range. There may be better cams but I discovered the Lunati Voodoo series cams do it well. It will give you a little lope at idle and still be very streetable. In my '78 ElCamino with a 355 and 9.5:1 it gets about 17-19mpg with a Q-jet.