You're best off talking to the 505Performance folks. They have complete swaps you can do, or they can have theirs built to the point you bolt your leftover undamaged parts up. It's all about $$$$
I have looked at their kits, and best I could tell, they're designed for you to use with your good block. I'd say you may be in trouble if you snapped a piston or rod in a chamber.
Most of their kits are new upgraded parts with coatings vs. what many guys scavenge from the old 4.2 inline six motors and do the cheap stroker builds.
With zero machining (best I can remember) I can build a stroker with parts from a 4.2 for just the cost of that old motor. If its free, them I'm building a stroker for free. But we all know nothing is free when working with jeeps or motors...and especially jeep motors.
Do some searching on here, unless you're just wanting to but the built block from them. I'd still spend the time on the phone with them to answer all the questions you have before you purchase. You're most likely looking at a $4600 investment.