You’ll probably gain as much or better airflow just by going to stock Vortec heads as you will porting the older heads. Plus your compression ratio should be better with Vortecs. I’d have to agree with Tech Inspector on your rear end gears. At least check and see what gears you have but I think factory gears on that car is probably a 3:42 or a 3:73. Anyone know what the 84 ‘birds came with?