Originally Posted by 2000SilverBullet
Not changing springs to at least 90 lb LS1 would not be wise.
Not for anything above 5500 rpm IMO.
Under 6k with stock springs should be fine. Personally, I would change the springs if it were my own car, mainly becuase I would spin to more than 6k, but also for the peace of mind. But, many people have no problems running rockers with stock springs.
We have 1.9 rockers in the SSEi (and have for 90k miles (car now has 160k on it)) and the valvetrain is otherwise completely stock. It has a DHP and shifts at ~6000rpms. It gets no valve float and we've had no problems with it. Our Monte Carlo also has 1.9'* with stock valvetrain with no problems. It has significantly less miles than the SSEi and has a stock PCM so it doesn't shift as high as the SSEi, but it doesn't seem to have any float problems. We only had float problems in the GTP at over 6k rpms which was actually suprising since it had OR pushrods, and what ZZP at the time called 85lb. valvesprings fixed that problem, the car ran all the way up to 6600rpms with that setup with no float problems at all, shifts were (and still are) 6250rpm and it never showed the slightest problem. When we installed the XP cam we left the "85lb." valvesprings in the car and it still performs great, we've had no problems with it either and it still spins to 6600rpms just fine.
I don't think it will hurt him to try to run the stock springs and see how it works out. If he does indeed get valve float then he may want to go to some stronger springs, which yes will be a lot of work on his part to tear it apart again, but if he doesn't need the springs that is a good amount of money he can save for other mods. But installing 90lb. springs should definately garuntee no problems.