Yes a fly cutter is the way I plan to go. I have a 5c index spin jig. It
has
10 vernier holes and a 36 holes plate Enco part #891-6020. So 18 spaces
is gotten without using the vernier.

Spin jig should work fine. Turn your part in the lathe first. Look up the OD
in machinery handbook. While still in the lathe turn yourself a handle to
go in the 5C collet you plan to use. That way everything is right on center.
I'd also bore your pulley hole at the same time.

I looked up the specs for tooth form in the handbook, used my baldor diamond
carbide grinder with angle table to get the angles just right and then an
optical comparator to get the width and radii just right. But my job was for
a servo drive on my CNC, I needed to be real fussy, no backlash allowed.
For your app, I bet you could just grind the cutter to fit an existing
pulley.

Good luck

Karl