I got a response from Holley and here it is. I have decided to change the pump to a 15psi unit. I didn't spend the extra time and money installing a pressure regulator and return line for nothing.
From Holley Tech deparment
"If you are using a Holley carb, 6 psi should be fine. Since that pump has a simple non-adjustable spring loaded bypass, a 1 psi pressure difference from the rated 7 psi wouldn''t be uncommon."