I think 10# on a slant would be plenty. Turbo's will get you more but at what close. You need to think about reliability and the belt driven superchargers are a bit easier to control it seems.
that's a big spend to be limited to 10psi, on a low compression slant I would want to see 14-16psi ( that's just me ) they run more boost than that on the little 4cyl. in the chevy cobalts ( those are 9.5 to 1 motors ) and run much higher boost
