Either can work very good on your combo. Myself I like the Holley Double Pumper carbs best but I am always looking for the best performance also. But I have used and seen others use Holley vacuum secondary carbs that have worked very good. In todays world either will work good as its more of your preference of which you like best. And the mechanical secondary air valve carbs also work good. That's what the Quadrajet , Thermoquad , AVS use and most AFB's even use a weighted secondary air valve. Myself I use the DP on all my cars as we have a 750 DP on my sons Dart and I run an 850 DP on my 63. Both cars are auto cars and both have great driveability on the street and track. Years back I ran a 750 vacuum secondary Holley on my 383 Dart for a bit until I got a 750 DP. And the car was actually ran just about the same et in the 1/4 mile with both. For the most performance out of a car I like the Holley carbs best but that's just my personal preference as I have seen the others also run great. For your car and with your plans I would run the Holley 750 DP carb myself but I would have no problem using the Holley 750 vacuum secondary carb if you prefer the vacuum carb. Good luck which ever you decide. Ron