what kind of horsepower?

hi, the 1968 to 1971 340 had 2.02 valves, the 68 -70 had the AVS carb. the 71-73 340 had T.Q.carbs. the 68-71 340 were rated at 275 HP. the72-73 were rated at 240HP. thr lower ratings were net with all accesories on.
the 71 340 and the 70 340 6pac had 915 heads, both had 2.02 valves. the 68- 70 340 had 894 X heads. the 72 -73 340 had 915 and 587 heads with 1.88 valves. the 72-73 340 makes a lot of power in spite of low compression.
this info is from mopar and NHRA, this is correct for building a legal stocker motor. the 72 -73 will have 9.40 comp, easy by decking block and cutting heads to min cc (64.5) with a .039 gasket.