Reversed Carb Throats
Well, maybe. RallyBob had warned that the "Pinto" style carb and Holley, with the reversed throats, can cause the outboard (I believe) two cylinders to run lean, due to the primary throat being inboard. I guess the theory is the flow path is shorter to the inner cylinders, so the outer cylinders tend to run lean. Now, when I look at a stock down-draft manifold and compare the flow path of a carb with an outer primary (such as the stock Solex and Weber 32/36 DGV), I really don't see much difference with the path that an inner primary would have. But at full throttle (with the secondary open), the condition is reversed. That is, the outboard secondary path of a Holley or DF Weber is better balanced than the DGV Weber. My bet is that the DGS Weber that Chris has is the best for balance, since BOTH throats open simultaneously.
And I had a Weber 32 DFM (a performance version of the dreaded "Pinto" carb) on my GT for about 50,000 miles, during which time it was run hard and put to bed wet. When I rebuilt the engine (at a total of 103,000 miles) it was in very good condition, with no difference in valve wear or other lean-related conditions. Now, as they say about gas mileage, your experience may vary.
The biggest problem with the reversed throats is the linkage has to be reversed. It took some monkeying, but by simply rotating the bell crank and replacing the pin on the throttle linkage with an offset pin, it worked pretty darn good. As for a Holley or Rochester, you will probably need to convert it to a cable, which is a bit of work, but eliminates all the inherent problems with the stock mechanical linkage.
HTH