Yeah, my 416 with Scat rotating assy needed mallory metal to balance it also. It has H beams I think. So does my 540 but it has forged Eagle stuff including H beams. I couldn't find what the 7.1 chebby rods were made of but they claim the kit is structurally good enough for 1500 HP.

At least they are steel rods so I don't have to worry as much about snaping one as I shut down cause my car doesn't have a N after the 3.