Vinnie nailed it. As I said, it's plenty "doable", just $$$. Hard to argue with virtually ANY BBC combination for a specific application when budget and parts are "right" with a good builder. And all the chatter about 496 is absolutely correct. GREAT street engine. But your block won't "fit"...
Since you have nothing but a bare block, you have a ton of choices. What was said about "shelf" pistons is correct. Hard to find for the "good" ones. "Custom" pistons have become far more popular and available in the last 10 years than they used to be (and less expensive form certain makers). With all the stroking and boring and rod length changes going on, "custom" engines are full of them. In another thread for a "torque" engine, I described a "428" BBC, using a 396 block and 454 crankshaft. EXTREMELY powerful for it's "size". It won't rev "quick" like a 427, but it will drag one backwards down the street. For a "pump gas street" application, a very good approach. This is particularly true in a heavier car.
With dual quads (properly set up, of course), modern heads and a good street roller, you have the makings of a SERIOUS BBC. I like it!