340 Block Bored to 4.160????? Help

in my opinion there is no such thing as "max. overbore". I know there are 318´s around that were bored to 4" after sonic check - could be that the previous engine builder found pretty thick cylinder walls. Ok, going to 4.160" is pretty big for sure, but i would not call it impossible. Pistons must be custom made or adapted from another application. Check the casting no. - is it a stock block? Could be a race block with thicker walls / siamese bore....

I doubt someone would search for Pistons in this size without checking the block - but of course i could be totally wrong ;-)

Michael