Largest displacement of a factory 440 block?

528=4.325 (std bore 440) with 4.5" stroke. 535 is that plus .030 over. I wouldnt bore beyond taht. And beyond 4.25 stroke, you need external pickup(s). 505 is 4.25 with .030 over. That's at the shop for me now. Usues 440Source's kit. That means chevy size rod pins and rod big ends, so it clears the factory pick up (supposedly..but I'm sure even if it hits a little I can clearance a bunch...) That's the easiest and biggest. Also, you really should have any block built with more than 4.15 stroke sonic checked to make sure it will last.