For applications that are for general fun and performance I prefer Vacuum as it is more forgiving being that it is not as sensitive to tuning. If you are looking for every last HP then a double pumper might be the way to go, but they can be more finicky with throttle response.
With what you have I would probably use a Holley 3310 as it is a 750 Vacuum secondary setup. If you have an open engine compartment and you don't have to worry about LEO bugging you about "marine hardware" I would go with something like this.
Like Hammerdown said, there is no reason a vac secondary can't deliever the same top speed as a similar sized DP. It may give up a little on a well tuned DP in acceleration. But it doesn't have to give up anything on top speed. It may need a secondary spring tuning to equal the DP on the top end, but thats about all.
With a dual plan manifold and a mild performance engine, its not going to accelerate all that hard anyway.
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