I am sorry but I know very little about any automatics. I have been told by more than one reputable source that it is dangerous to neutral a 400 tranny. I guess I missed or didn't see anything about him using the 400 here.
I always ran a clutch shifted 4 speed in my old car when it ran what it ran so going to neutral was easy for me.
If someone busted a 7/16 bolt factory LS-7 rod at only 7,300 rpm there had to be something else wrong or the rod defective.
Not only me but I know many who have turned that rod over 9,000 rpm with mucho horsepower. Years ago in the early and all through the 1970's that rod was heavily used in both NHRA and IHRA Pro Stock in the early years when Richie Zul, Dick Aarons, Wally Booth, Bill Mitchell (Motion Chevy) Warren Johnson, Sonny Bryant and many others were running with the stock block, stock rod, TRW Piston combinations and they were all buzzing the little things to 8,800 to 9,000 rpm back then.
I do definetly agree that a better rod would be best, but will also say if his engine was clearanced right and has good lubrication and he takes care of them the 3/8 rods can work fine with moderate powered engines at less than 8,000 rpm. MY little 461 with the 3/8 Dorman HPX Bolts did not even have floated pins. They were pressed. Didn't keep a 2985 lb car from running 8's in 1984. Had some really great heads though. LIghter weight pistons can also be a benefit.
Ed