In the same boat as the OP, about to put this T60R on a stock motor.
FWIW, AMR designed this turbo for streetable high-end. From reading through nasioc and iwsti it really seems to wake the F up at 24psi. 21psi seems to float around that 400 mark, +/- 25whp for varying conditions. That's about where I'll keep mine til I have rod/piston shortblock in hand. But OP's setup should be spooling up faster, should hit 21psi before 4k rpm.
How about an update