How Big can a 5.2 get?

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What size can a 5.2 be bored over? I know alot of older 318`s been bored for 340 pistons but how about magnums? I just got a 5.2 thats been sitting and its got rust in the cylinders so an overbore is a must...
I think I remember seeing about .040 is the max. Anything more than about .030, I would have it sconic checked.