i have a 71 charger with a 360, its suppose to run to 6200 rpm but im losing power at about 4800. so im switching from a 650 to a 750 holley, old performer intake to the edelbrock performer rpm air gap and putting a carb spacer on to clear my hood because i have a gnarly dent where my engine hit the hood and im just gonna cut it out and have a scoop. i have a open and 4 hole carb spacer, which one should i run? it is a dual plane so i want to go with the open...but i dont want to lose my bottom end. ill be running 4.10 gears and a 3000 stall. car weighs 3500 pounds.