ALL of the Holley "double-pumper" carbs were designed as "race carbs" in the sense that they are intended to be used with non-stock, aftermarket tube RACE headers. The term that Holley uses/used, is "header scavenging". Scavenging tends to lean out idle a/f levels.
What that means is that the idle A/F ratio is set by design to correct the fuel level at idle WITH HEADERS to be correct for the larger exhaust. This means a heavy, noticeable "gas smell" to the exhaust.
I ran a 4779, 750dp for years and just got used to the heavy exhaust smell. It is as bad as the idle smell of the Weber 48ida setup, which will smart your eyes.
You could bring it to a "carb tuner" and they could modify it to have a leaner idle but it isn't really that simple to do since it requires internal changes to the idle fuel circuit.
The simplest thing to do is to change to a carb like a 1850 or a 3310 and that will give you an idle designed for a cleaner street idle, i.e., a late 1960's "street idle" which is important to note, not able to be clean enough by today's emissions standards to be street legal.
If you are in a location like California, that still uses a tail pipe sniffer as part of the annual State emissions test, even those two carbs are going to be too heavy and you are going to need to use something like a '85 Mustang GT carb.
That one is NOT AN "1850" BASIC DESIGN. It is designed to idle with an idle of 14.6:1. That ratio is locked in and you cannot change it. It is around a 600cfm carb with annular boosters in the primaries and vacuum secondaries or you can go to an EFI conversion like the Holley Sniper system which is designed to replace single Holley 4v carb applications and will give you a clean idle.
Other then that, you are in for quite a bit of work to get your 650dp idle levels down.