I've never used NOS but I have built several pump gas N/A 400 stroker motors that made in excess of 700+ HP for street and strip use, I did use Ductiile iron main caps and ARP main studs in both them with a 4.250 and 4.300 stroke cranks. Both of those motors had the dog snout beat out of them for as lot of years and passes at the track I am racing one of the early 230 thick main web blocks now on E85, it has the Mopar ductile iron main caps on it also with a 4.25 stroke crank, I haven't torn it down yet as it has lees than 200 runs on it so far so no feedback on it yet the big thing about all the 400 block is the cylinder wall thickness, just like all of the B and RB motors, always sonic test them before using them I wouldn't use any stock block that I hope to make north of 900 HP unless it was a Gen 2 426 street Hemi block that was a unhurt virgin