670 vacuum secondary vs 650 double pumper

Im never going back to a vacuum sec Holley. the TQ is another story. Im a sucker for the moan that baby makes. Small primaries are nice on a stick car if, like me, you like to romp on it at low revs.But the bigger 750DP can be tuned to respond almost as well, and it pays bigger dividends up top, at the track,and my a$$dyno says midrange too.
-Having said that,I think my next carb will be one with metering rods.A metering rod carb can be tuned to post some good gas mileage numbers. Numbers a Holley type carb cant usually touch.
With the size cam youve got, gas mileage is still on the table. Unfortunately those 3.91s are past borderline, Taking your revs to 3150ish@65. However, a pumpkin swap is only 90 minutes. Then on a cross country trip, the money you save on gas can almost buy you a room at the other end.And the reduction in NVH is most welcome.
-Holley and holley-type carbs can be excellent carbs, especially at the track.
-But the metering-rod carbs,on engines with street-friendly cams,in the hands of a sharp tuner,can do so much more. Especially one with multiple boosters and a spread bore.
-Given the two listed options;as to size, its a coin toss.Ima DP fan .Stick cars like DPs
JMHO