The 86x86 is a perfect motor to rev high as it is a square motor. People have revved the sr20 really high. All that needs to be done is build the bottom end(pistons, rods, steel sleeves) and head (solid lifters, big cam, springs, retainers, etc) to support the revs and actually have a cam/turbo setup that will make power up there. No sense in revving 10k+ unless you are going with a 70mm+ turbo imo.