Neverending carb questions/dilemma

[RapidRide2]

I am not trying to run this in the dirt. However I need some possibly unbiased (yeah right) opinions for my situations. 350 ci chevrolet in an 83' GMC. My engine will be putting out 285-295 h.p. yet with a somewhat steep 405-410 tq. at 2000 rpm's with a hydraulic roller. My goal is to get as good of a running street engine without losing economy or even possibly gaining some. Is it possible to get a holley 600cfm vac sec. to get as good as gas mileage as a Quadrajet??? I know almost nothing about a q-jet. From racing experience i know alot more about the holleys. Would the edelbrock carbs offer the smaller primaries of the q-jet??? On this engine i would give up 6-8 h.p.@6000 rpm's for 2-3 mpg's, however, i am really comfy with the holley design. Thanks to all who reply.