Well, I am not a Holley guy, nor an expert, so I had to web check your carb. It seems the 4150 has mechanical secondaries which is not always the best for a street car unless you have some 3.90 - 4.33 gearing, high stall converter if automatic, or a desired close ratio 4-speed. Vacuum secondaries are much better for the street and offer a smoother transition when the secondaries do open as the engine demands more air/fuel. Mechanical secondaries just pop open immediately when you mash the gas and if the engine isn't pulling enough rev's/air flow through the intake, they open too quick and the engine can bog down or even back fire through the carb before it picks up again. This is why the need for the gearing or higher stall converter to help get the engine to rev faster more quickly.
Next issue could be the large cam - too big. Big cams are typically aimed at upper mid-to-high RPM's which sounds like what you have by your explanation. The cam profiles dictates your torque and RPM range where the power really turns on. For a street engine, you would be better off to select a cam for lower end-to-upper mid range RPM's. Not knowing any more about the engine or what is inside it, it would be hard to advise what to do.
The best carb/intake selection is exactly what the factory put on the engine, Quadrajet and matching intake. 750 CFM's, small primaries to cruise on, big vacuum secondaries to kick the power on. The small primaries can provide better gas mileage while pulling higher velocities of air/fuel creating a good transition for the vacuum secondaries to kick in.
So it may be you have the wrong carb for you application, the wrong cam for your application, or both. The first thing I would do is go with a vacuum secondary carb whether you stick with a Holley or go with a Q-jet/intake swap. The vacuum secondaries may help if the cam is a little too big.
Take my advice with a grain of salt and hopefully others will chime in, but that's my opinion on what may be going on with what you have. Fuel injection? No experience using any of the new systems.