[SHO411]

don't know much about the turbo parts never had a KA but, upgrading the pump is as easy as finind one off a 300ZX TT, rebuilding is a good idea.
Ka is not good at top end power, it is a truck engine, has good bottom end torque but can't rev high, for that you will need the other japaneese counter parts. You could precision balance your reciprocating mass and lightened for high RPM, have a head job, and better valve train, this will give better RPM capabilities and still retain the fast accel of the KA. then you will have the best of both worlds but holes in your pockets.