Just buy a supercharger and put a blister on the cowl to make it fit. They make em. You will spend 1-3 times as much in the end trying to roll your own (over and over again) when an off the shelf solution exists.

Speaking from experience here...

If I had the right equipment, and knew how to calculate the performance in order to design and produce a shaft driven coaxial blower I would.. but I dont..