Choosing a replacement carburetor

[Ride The Snake!]

Hello all. As you can see I'm quite new to this forum. I've got a '70 GMC C1500 (350 cid with 4 spd manual) that I've had for a little over a year. I've been learning to wrench on it bit by bit, but by no means do I qualify as even a shade tree mechanic. I most recently set about rebuilding the Rochester 2G that came with the thing after it started leaking fuel and later developed a massive vacuum leak. The PO seems to have modified the thing, as it's lacking parts for the choke and has several of the small vacuum tubes on the back side capped off. After rebuilding it myself and finding that it still seems to leak fuel and air, I've decided it might not really be worth my time messing with it any further. The lip on the mating surface between the air horn and fuel bowl was mashed flat in places anyway, so I'm not confident it'll ever form a lasting seal.

Which brings me to my real question--what sort of carburetor is recommended for replacement? I really don't know what--if any--modifications have been done to this motor. From the looks of it, it's had a motor swap. It's clearly a small-block Chevy, but I really only have the seller's word that it's a 350 (I know, I need to look up the engine codes). It wasn't advertised as having any sort of valvetrain upgrades. I don't know what intake manifold it has, just that it worked well with the 2G. When it ran fine, it made plenty of low-end torque. The truck's got a dual exhaust that looks stock save for the mufflers themselves.

I guess I should be looking at something in the 600 cfm range? Any advice beyond that? I know I'm not coming with a great amount of info on my engine, so I expect any advice to be ballpark/guesswork. I'm not trying to make this thing a hot rod, just a street truck with responsive low end and enough balls to get up to 80 mph easily.

I've heard Quadrajets are great if you can get a quality rebuilt/remanufactured one and get it tuned just right. However, at this point I'm not confident in doing that myself, and I honestly would prefer the reliability of a new carb. My dad's got a Q-jet from his '71 Suburban that he tried to rebuild, and eventually got some sort of Edelbrock 4-barrel after being dissatisfied with the Rochester. His motor is tired as **** though.

Apologize for the long, rambling post.