what needs to be changed in a 72 340 to be like a 70 340?

Sounds too much--what else was done besides the header swap--I am running the same exhaust pipes and mufflers as before. My shift was at 6,500 (aiming for 7,000 this time and only that "low" cause its got kb hypers-not forged.

Sometimes the carb is jetted too rich and headers help lean it out.

Sometimes its not til the headers are on before somebody fines tunes everything-jetting, timing-ignition up grade, I run msd 7al and hvc coil and high end wires with heat-shield to fully stop the wires from shorting to ground..my old msd 6 was ok but the 7 system was a noticeable improvement. Helps to burn more of the fuel.