I don't have the Spool built short motor but I purchased the 3.4 rotating assembly and had my engine builder do the work.
Airflow through the head is hugely important, don't skimp on this. I personally wouldnt put cams bigger than 270 as you don't need the revs especially for street use, make sure you degree them with a dial indicator. With my 26 head and 1mm OS valves, 10.8mm lift and 260 degree procams, mine makes peak power just before 8000rpm with a broad torque curve from 3000rpm. Turbo is a 6466 with twin-scroll 1.0AR hot side. Has made over 800rwhp on 28psi but its useless at this power, I actually prefer gate pressure which is 14psi creeping to 19psi and about ~550rwhp