I've got a 1970 production SCJ 4-bolt block engine that is all finished, in the car, and read to start in a couple of months when the rest of the car is complete. Target is street / strip. Aluminum SCJ heads, mechanical roller... nasty but not insane. Turbos may come later. I just saw the article in Car Craft about their Boss build up and now I'm worried about piston rock. Their early block and 4.5" stroke is exactly what I've just built and they unequivocally said this combo pulls the piston too far out of the cylinder on the down stroke. Do I need a late model or motorsport block to be safe with a 4.5 stroke?