I have recently used them both on my 327. The holley was a 650 dp and the edelbrock was a 600 performer series. I got the holley brand new. It reved waaayyy faster and even changed the sound of my exhaust a little (for the better) I literally got 8 miles to the gallon with it. It was running a little rich so i jetted it down til the plug looked nice and still it got horrible fuel economy. I drive mine daily so I bought a used edelbrock 600 for 25 bucks. It was pulled off of a mud truck for the first time in a few years and was covered in mud. I cleaned it up and bolted it on, set the idle and mixture screws and She fired right up. The truck ran much smoother at idle. Sounded like a throttle body truck. It reved a little smoother but not as fast. I doesnt quite make the peak power of the holley but has nice throttle response and smooth acceleration. I havnt even jetted it yet and im getting between 10 and 10mpg turning 33" mud tires on a 67 swb 4x4. If I was builing a race car it would be the holley. For a driver or for a non carburetor expert like me, You cant go wrong with the low price no maintainance very reliable edelbrock. Good luck in your quest friend.