What is bore and stroke of a chevy 496?

4.310 bore X 4.250 stroke -- basically a 454 bored .060 over with a 1/4 inch longer stroke crankshaft as compared to the 4.250 stock bore size and 4.000 inch stroke of a 454.

Just as an aside FYI, 427's have the same stock bore size as a 454's but have a 3.760 stroke.