Just some on paper math: to gain an eighth inch of stroke (4.375-4.250= 0.125") you'd need the rod journal to be offset an addit'l 1/16th (.0625") so the journal will need to be reduced at least a 1/16th , maybe a hair more. On paper I am GUESSING that it would be doable as you have .175" of journal reduction available (2.375-2.2=0.175") and you need .0625" of that. I'm assuming you have the rod journal width differences between Mopar/chebby taken care of on this. EDIT 4.400-4.250= .150" stroke increase & needs at least .075" journal reduction and you have .175. Hell I'd go 4.5 & 440 source has the pistons for it (using 7.1" rods/.990 pins)