You can rev an ls crank & rods to 8.5k-9k with no problems.

People blow motors up with ls r/s ratios because they don't drive them properly & or don't build them properly in the 1st place.

The ls r/s ratio makes it a little more dangerous then lets say a GSR or ITR r/s ratio....

Personally, I would run ither setup depending on the availability of the components.

If you "have to be at 9k every day" spend a little money & go with a GSR/ITR r/s ratio