I'm in the process of going 430 cubes - 4.080 bore X block and a BPE 4.125 stroke

I'd call BPE - Rod he sells a 4.250 stroke, included in a nice rotating assembly that would have put me at 444 cubes

The reason I did not was I am using a ported eddy - and if I were to upgrade to the even longer stroke - I should go to a better flowing head.