i am running a 4053 holley 780 on my 69 302. it is ok but it has a dead spot when you take off that my engine shop cannot do anything more to stop it. after you get past that it is sweet running. they suggested for better drivability that i run a 650 4 corner idle dual feed. what do you think. it is pretty much a stock engine that has been bored. lt1 cam. 3:73 rear.
thank you

I think you will run out of carb cfm. Need to figure out were the problem is. Suspect you may have to much idle speed dialed in and the idle slots are just about totally uncovered. If so you will have to drill two small holes in the primary butterflies to compensate.

Larger Dave

Find another shop either they don't know what they are doing or they are crooks. The stumble is an easy fix if you find someone who knows what they are doing.