centrifugal compressors don't work like that, boost is dependant on the square of rpm. You need a twin screw if you want boost from 1500 to redline.

Is it a good idea to be twincharging with the engine driving a centrifugal? Wouldn't a PD or a twin screw be far better off?

If you can afford to do this stuff, I think a single TS would be the best option in terms of packaging and piping and serviceability.