Re: Holly carb 12R-10658B?
not necessarily. if you have a mostly stock 350 what you need is a vacuum secondary 600, not a 750DP. It'll run bad and get horrible gas mileage. Putting a 750DP on a stock or near stock 350 is one of the biggest classical mistakes in rodding.
Sell it, but a 600 or 650 Vac secondary. Or, just buy a quality rebuilt Q-Jet, which would be your best bet. NAPA or a Holley brand rebuilt, many AutoZone stores have these. Are you aware of the many hassles around linkage, vacuum lines, adapters, spacers, fuel lines, etc there are around going from a Q-jet to a Holley or other performance carb?