How high do you want to rev? My LS1 has an upgraded valve train and it will rev to 7k rpm... It runs out of power in the 6000s anyway.
I was kinda hoping something insane like 9k. I'd love to keep it N/A, and just rev rev rev. And the powerband can be sorted with a cam. I'd think Solid lifters, hardened pushrods, titanium springs, nitrated valves, maybe a balance on a de-stroked LS would be bonkers.
My dads running 300-320 whp on his tranny. But i think its a different tranny than the NA. But his lsd is whiped and he's rebuilding it with a new LSD and shorter final drive.
Didn't you say his tranny was worked over anyway? The LSD ones are different, yeah, though I don't think the gear strength was changed.