Best Way To Cut Tapered Key Seat

I need to cut a new tapered gib key keyway in a splined clutch hub. What is the best method, make a new bushing with the correct angle machined into the bushing or just use my existing plain bushing with a tapered shim to get the angle I need? I haven't ever had to cut one of these before and machinery's handbook was a little weak on the details other than giving me the proper angle. It is a 1/2" key going into a 2" bore.

Hello, my name is Brian and I'm a toolaholic