Shanker, I have had success with both carbs, the Holley does seem a little bit more tunable and I like the drivability of the Eddy. Can you list some of the reasons why you are switching away from the Holley?
I drive a 75 Duster 360 w/ #'s engine and rebuilt w/ Badger Flat Tops, 340 Resto Grind Cam, 1970 340 intake and 1.88 J Heads infront of a built 727 and a 3.21 8.25 sure grip.
The car runs extremely rich, is not very tunable to me (but thats me w/ 0 knowledge of carbs) and gets about 9-11 MPG.
My 70 Coronet R/T, #'s matching 440/4bbl/727/3.32 8.75 gets 20mpg doing 70 on the highway, I think that this Duster should get about 15-19 driving it easy on the highway 65-70mph
I put a Eddy 750 (1407) on my Coronet, spent 10 minutes tuning it, and havnt touched it since.
I recently moved from Waco to Coprus Christi so we are now at sea level, which shouldnt affect it much, but when I stand on the throttle, the drivers side bank just pours black smoke out of the engine