Edelbrock makes a "performer" package that has heads, intake and 600cfm carburetor designed exactly for the rpm range you want. a 4 barrel carburetor is a 2 barrel until you need it, when it flows extra air/fuel when you romp on it (vacuum secondaries and mechanical secondaries open up from either engine vacuum or from the linkage). Usually 2 barrel carburetors are a compramise because they flow more air (usually 350cfm is an averige size i've heard of) at part throttle than a small 4 barrel so there's more fuel consumption (compared to say a 600cfm carburetor) if you're driving normally, and there's no top end to them because of the restricted flow. Also fuel atomization has more to do with swirl and the carburetor venturis (as well as the individual diameter of the venturis) than how many barrels a carburetor has. A grossly oversize carburetor won't idle for sh/t and will bog and have horrible fuel economy, but a nicely set up 600cfm carb would be perfect for what you want. I usually get 16-20mpg with lots of city driving with my 4 barrel so it's not bad. Good luck, hope this helped.
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'84 Mustang 5.0 LX
My car