what is my best bet on carburator

[Mo65]

As I probably mentioned before, I have a rebuiled stock 302, stock heads, cam,etc. It is factory 2v, 2 barrel carburator.
The slight modifications I have made is
petronix flame thrower coil
petronix igniter to make eletrock dist
try Y headers
dual exhaust, 2 1/4 super turbo dyno max with balance tube
8mm wires.
Nothing fancy just want the power of an 8 cylinder muscle car.
I am running an aftermarket Holley 450 cfm 2 barrel carb that was shelved for about 5 years. It is the first time I've started the engine after I 've installed exhaust and carb, so I don't really know how the engine should run like with the exhaustsytem and stock intake I have. The carb seems to be sticking, but I am not sure, and it does not idle right on low idle speeds, but at high rpms it runs fine. There is no vacum leaks, timing problems, ignition problems, nor gas problems. I was told by some people that the carb is starving from gas beacuse it needs a bigger carb, like a 500 or 600cfm 4 barrel because of the double exhaust and mild modifications I did. So I was considering changing it to a 4 barrel carb, and obviously changing the intake to a perfomance one. But at the same time not sure if it will correct the problem.
I don't think the 450 cfm is a small carb to make my car idle the way it is.
Even though, I was considering changing it to a 4 barrel whether the problem would or would not be eliminated. Just to have a 4 barrel carb, because most people criticize an eight cylinder engine with a 2 barrel carb. The question, is is it worth changing the 2barrel to 4 barrel with the mild modifications I've done? I donot plan to install a aftermarket competition cam or heads.But I was planning to intall an perfomance intake like the Edelbrok. But at the same time I heard that there is not really A diffrence if a competition cam is not intalled. If I install a 500cfm 2 barrel, or a 500cfm 4 barrel, is there a diffrence in performance. Will I feel a diffrence or the same? I am not really interested in top end speeds but more in low end toque, but at this time I just want my engine to run right once in for all. And spend the least money posible.Can a 4 barrel intake be installed to the heads that were originally for a 2V. As mentioned, the car has now dual exhaust. So I would assume it needs more for intake, as some people speculate . But what CFM carb would I need for my application that has stock heads, stock cam, and all the information I mentioned above? 500 or 600cfms


Please help me if you know the an answer of one of my questions and feel free to answer the question that you might have the anwser to.
And advise me on what I should do.
Thanks