A little more work got done today.
I pulled the bushings from the shock and measured them. I'll replace them with spherical bearings which should work better.
Ohgood had the right tip on cutting the sprocket. I put it in the big lathe, set the speed as slow as possible and it cut quite nicely. Slowly, but nicely.
I put a countershaft in the engine cases that are mounted in the frame. Then fit and adjusted the chain.
This is with the chain tension adjusted and the wheel at full extension. The slack looks pretty good, there won't be too much work for the rollers and guides to do.
It's a long bike.