If your pulley's are 1/2" pitch (square cog pattern) with a 39 upper and a 31 lower you will be at roughly 20% underdriven. I don't think you will make your target boost with a 20% under drive. If you swap them to 39 lower and 31 upper you will be at roughly 25% overdriven, which I don't think is a good idea on a bascially stock engine. Most people run a 10% underdrive which would be a 34 lower and a 38 upper. I would shoot for that combo to get your target boost. The pic below is a 8mm pulley.
1/2" pitch
http://www.blowerdriveservice.com/pitchpulley.pdf
8mm
http://www.blowerdriveservice.com/8mm.pdf
