Neither. Go with Quickfuel. I have been through a lot of carbs in the last 3 years and really like Quickfuel. If you want choke and vac secondaries look at these http://www.quickfueltechnology.com/carburetors-ss-series/vacuum-secondary-1.html Give Bobb a call at Finishline and he can help you out.
i have just bought an holley 870 street avenger for my miled performance 455 . is the holley good for me
I noticed that Summit Racing doesn't sell the BG Speed Demon so that must mean something. I seen that you can get screw in air bleeds with a Holley also. I like to use a 1 inch spacer it seems to get a little better power and keeps the heat farther from the carb.
I picked up a "like new" 750 DP for $175, so I think I will just run that for now. It is an easy choice for me because I know them so well. I can always get an HP center section if I need more tune-ability later.