Well im planning on turbocharging my 12a. i'm thinking about going with a holley blowthrough setup.
I finally figured out compressor maps, and it looks to me like a mitsubishi 20G would work good at about 15psi, but not completely positive.

If you think something will work better throw it out, and please oculd you explain why it would work better. Thanks

 

The 20G will make low to mid 300's on a series 4 Turbo II. Some variant of it comes with the Greddy kit which is still available.

 

Hit up robert at rotary shack. He is the king of 12a turbos
www.rotaryshack.com