The woodruff key on your 361 should be a separate piece. A new key should take care of your problem. You have a tapered crankshaft so if you line it up correctly you may be able to tighten it without a key.
Hi Lester,
If you are just trimming the log to fit on your mill standard skiptooth chain should work just fine. Ripping chain cuts a bit slower but leaves a smoother finish.
One of these should work for you if you are converting from a spur sprocket. If its just the rim itself small spline 3/8 is item number 18720 and the small spline .325 is 11892.