Cruising miss (lean)

Motor is a 360 with 340 race heads from edelbrock, edelbrock flat plain intake 750 proform. I've jetted up the front and back to 76/82 respectively. Replaced my powervalve, and cleaned the idle nipples up top and also moved the timing around. As well as putting a new coil, plugs, wires cap and rotor on it. It will accelerate but when coming to cruising speed at a level rpm and speed it feels like it's missing lean missing. And the plugs aren't dark enough still whitish.