Factory underrated all 340’s at 275hp the 4 speed cam, the t-quad with the better intake in 71, AVS 340’s around 300hp, 71 340’s closer to 315 and 6 pack a little more. NHRA pegged the actual HP back in the day. 340’s and Hemis were underrated, 383, 440, and 440 + 6 were a lot closer.
My dream engine has always been to build a blueprinted 71 340 using the 68 4 speed camshaft. Stock cast iron intake, Thermoquad and all. Maybe hang a set of good headers off it. A body, 4 speed with 3.91s.