400 has the biggest bore but it's only 0.020" bigger than a 440 so not that big of a deal. Where shines is the shorter deck height (lighter pistons). A 440 is really to tall for anything under 500 cid so 400 is the better block for those sizes but 440 is better 500 plus cid. 383 is also a good under 500 cid stroker but cause of its smaller bore will be almost 20 cid smaller than a same stroke 400 not that big a deal unless going all out 600 plus hp cause of valve shrouding.
