Do not swap the pulleys from from
JS to SC like your mechanic said or you will make like 6psi of boost..lol..
Assuming you have the 2.8 serp side (9psi stillen) pulley I would scrap the 3.47 and go with just the 3.0. That alone will get you to 13psi. If you want more than swap the 3.0 to the 2.8" and get the 3" idler.
If you want power now since its at the mechanic then keep the filter off and do the 3.0 only which should get you around 16psi.