I will take some pics and post them tomorrow.
When I first dropped the stock sprocket on my wheel, I saw that the sproket center hole almost fit snugly on the machined stub on the wheel's hub. About .010 slack. I could center it exactly with 3 thin strips of paper card inserted at equidistant points when placing the sprocket.
The sprocket doesn't fit flush to the flange because it is resting on the spoke ends at the hub perimeter.
You can buy a stock, redimade,zinc plated washer that fits perfectly in the narrow space between the spoke ends and the machined stub of the hub.
The sprocket bears on this when bolted, and clears the spoke ends.
This washer is 1.5 id and 2.25 od. You will also need to accquire four flathead allen bolts, m6x20 and locknuts or 1/4 x1" sae. I had wrong measurements for washers in the other posts.
it, and the space that it fits is only3/8" wide and has to have four 1/4" holes drilled in it, so layout has to be pretty accurate.
Once the sprocket is drilled, I clamp it to the hub with the washer in place and clamp it with small c clamps and the paper strip centering shimis in place.
Then I take a drill and 1/4 bit and just barely drill the the washer thru the sprocket holes, to get a mark similar to a center punch. Or use a transfer punch if you got it. Mark the sprocket and flange for orientation.
Drill two opposite holes in the washer to 1/4 ". reassemble parts and align 2 washer holes along with sprocket holes with the 2 factory holes in the flange. clamp it all and drill , chamfer,and bolt the 2 holes. I use a 1/2 " bit for chanfering the holes.
Then remove clamps and drill/bolt other 2 holes.
Sometimes the nuts will interfere with the tack welds behind the flange.. Grind a 45 deg chamfer under 1 flat of the nut to clear the weld bead if needed.
I carefully grind the dust cover to a small enough dia. with a bench grinder so that it barely clears the sprocket hole, and put it in place before the brake arm.
Whole process takes me less than 1 hour.
Hope this helps.
Wayne