The end result with either one would be the same. I'd lean toward the factory carburetor as it is a perfect fit everyplace. The Edelbrock has a very slight advantage with the single MAB casting, but that disappears when you correctly calibrate the original carburetor for what you are doing.
I would get one of our kits, and we can supply tuning parts for exactly what you are doing. I'd also get one of our HP choke pull-offs, so the secondaries don't lag, and consider an E-choke conversion if the intake has been changed or heat crossovers blocked off, or if the stock hot air parts aren't in perfect working order......Cliff