Lots of impellers will make 40+ lbs boost but it's not the boost that makes the power. How much power are you looking to make? The next thing is compressor speed, most turbochargers run at 80 - 120,000 rpm thats a lot of gear speed. That will give you some idea of the compressor wheel you need, so you might consder a wheel from a belt driven blower and adapt it to your application, however as you mentioned the BMR guys did a pretty good job building a drive for a turbo compressor so it sure can be done.
You can buy impellers or even rotating groups from any of the people who advertise in the SCTA rule book.
Good Luck on your project.