Thanks for your input. The car does have a 1406 carb. The rear end gear is 3:55. The tire size is P245/60R14 and it is a 4 speed car. The carb has not been rejetted.
It's not getting enough air through the entire range of RPM and it's running sea level jets and rods.
East Valley and Phoenix AZ is at about 1000ft, so you aren't terribly rich, but the combination certainly isn't doing the engine any favors, with that cam and those headers. It would eventually start fouling plugs and without tuning, you won't get the throttle response you are after.
A 650 Holley DP is a good choice on a 4 spd, for CFM, etc. It depends on what kind of vacuum you are seeing on that engine, with that cam.
I think there are better carbs that use more modern technology for the street than a DP or AFB, but everyone will have their own opinions.