i have heard that nitrous pistons need to really have a minimum of 1.25 pin height to live.may be a wives tale but again piston manufacturer will be able to help you out the most.also stick with 2618 grade aluminum forge piston.no cheapie srp or mahle piston with the kinda nitrous your talking about.ross je aries diamond are some of the best
half of stroke is 2.1875.
good minimum piston pin height 1.25.
deck height is 10.2 *about*.
so subtract half of stroke and minimum piston height and that is ball park rod you will have.so my math says 6.7625 which will should work out with a 6.7 inch rod.but check with manufacturer like mark said try to keep piston pin out of the ring grooves...good luck