NHRA back in the day rated the 340 4V at 325HP. This was based on 1/4 ET's, vehicle weight, gears and tires, using comparisons of thousands of runs and removal of engines for dyno tests.
The 340 six pack was rated at I believe I remember 360HP.
6pk nhra rated 319 325hp
340 295 low 310hp high
never 325 for non 6pack
never 360 for 6pack
blue printed stock 340 with a 750 carb makes right around 340 hp
intake carb cam headers dizzy with a 1/2 a clue 370 to 390 hp
