Start familiarizing yourself with holley tuning. I wouldn't expect to plop them on and have them run perfect right out of the box.
Not to mention how much more of a hassle it will be to tune the Holleys compared to a set of Edelbrocks.
The Holleys will have to be removed and the fuel drained to get the bowls off for jet and metering plate changes. Edelbrock metering rods are swapped easy enough and will only need the top off for jet changes.
The Weiand tunnel ram allows you to mount the carbs sideways to facilitate bowl removal.
