I don't have a Homelite 33cc here to refer to to make you a prop hub. I've got one in storage about 200 miles from here but don't have access to it at the moment. Do you have your original magneto flywheel? I often make prop hubs using the center cut out of the magneto to fit the taper on the crankshaft, and then make a prop hub to fit against that. I then make a collar that goes around that flywheel center piece with a magnet in it, and it is adjustable for setting the timing. How are you going to mount your sensor, and do you have a pic of the engine??

AV8TOR