Chevy 350 small block with rough idle, please help.

I have a 1946 Chevy truck that my Dad gave to me before he passed away, so everything i know about the truck i learned from crawling under the truck finding names and numbers and going on-line. It has a 350 sb with Edelbrock intake manifold (#2701 performer eps).On top i have a Edelbrock carb (#1406 performer series)with electric choke. There is no emissions or a/c just motor. The motor has hooker headers going through straight pipe to two 2-chamber Flowmaster mufflers. Transmission is a 700r4, nothing major just right to smoke the tires from a stop. Now my problem is that it has a very rough idle, i step on the gas it feels ok when i let off rough idle again. I replaced the spark plug wires (4 months ago) with Taylor wires, i replaced the cap & rotor with MSD products i also check the vacuum advance canister, it works. I also replaced the carb gasket, 2 vacuum lines (1-vac adv. to carb. & 2-brake at rear of manifold to booster). I checked the wires to make sure i did not cross them. I replaced the fuel filter and all fuel line, only 1- fuel line from tank to carb 3/8 rubber fuel line. I cleaned carb and adjusted the 2-air fuel mixture screws at the front of carb, i have them set at 3 full turns out. Any advice on what else i should check, please help. Thank you.  

What cam is in it.  
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?-Have no idea what the cam is, from what i remeber my Dad telling me it is just a regular 350 crate motor. When i took ownership of the truck i took it to a mechanic here in So.S.F. He did not say if it had a big cam in it, but he did tell me if i had no plans of drag racing the truck to just keep it simple the way it is for a nice street cruiser. With that said i would think it is just your basic 350 crate motor out of  the dealership or catalog.  

What is the casting numbers on the block and heads.  
Professional hi-performance engine builder

Horsepower sells Engines and torque wins races.

I think tha carb may have some trash in it, I would pull the top off of it and inspect it. Be sure to remove the needles first so as not to bend them when pulling the top off. I have had tons of problems in the past with these carbs idleing rough and open them up and wash out the inside with brake parts cleaner reassemble and they would run fine.