I wouldn't hesitate to spin them as high as they'd make power (around 8500).

 

Back from the dead thread...

I figured I would give you guys the update on my frankenstein. i finally got the car into the shop. The headgasket was not blown and the engine is now running smoothly. IT'S ALIVE! HAHAHAAHAHA I can't drive the car yet due to some other issues, but it's getting there!

 

im not to sure about the b series...but i know the f-series, which has the same revving issue has a beginning red line of 6200 with a 8 or 9k max....im sure the ls has a very similar red line..and im going to have to say that 8500 is WAY to high for a stock ls at least all the time.....8500 wont hurt it if you only see it a couple of times. ( i dont think) good luck getting that thing running.