The rough idle has a purpose ... thats a tight LSA
cam... which has more over lap.. the over lap is what
you hear and it makes more low end cyl pressure which
makes torque... for the HP and TQ you want to make, your
headers are too small, most likely you would need 2" but
maybe a 1 7/8 would work is the revs are low enough...
I'll let the other tell you what you need for your
goals.. but weed out some of the stuff you read