Not sure exactly what you ordered- I wrote a reply the other day, but must've wandered off and forgot to post it. It went something like this....
I had/have a Norton chainwheel maybe from a Commando era, that I planned to use.
The spline is the same, it is triple roller, same pitch, but too big a diameter for the plunger case...!
May work in a swing arm jobbie..?
Re- 'vapour -blasting', be same as 'aqua-blasting', or 'soda-blasting' (with sodium carbonate solution), I had a hub done with soda-blast, comes up good and led to believe a bit more gentle than sand or beads.
It's an easier/quicker option but wire wheel then acid/vinegar works ok, if you like getting dirty.