I can see where it would be easier to get pistons, I just personally have not seen a 318 thick enough to go .090 I know they all vary but my fathers 67 318 cylinder walls were between .150-.180 @ .060 over. Another .030 would be to much IMO to put a 4" crank in it. I do like the idea, I would build one myself. 318s are everywhere and very cheap. Any particular years the thickest? A square motor would be cool.