Now that I have the case opened, I found what is causing the noise. When I changed the ring, I also installed the back half of the prop adapter. In the process of tightening the left hand nut which is locking it to the crank, I gripped the opposite end of the crank with a visegrip to hold it from turning. Somehow while tightening the nut, the crankpin broke loose from it's press fit in the two crankshaft halves and now looks crooked. If I rotate it backwards, it straightens out and there is play. Then rotating it in the new running direction, it shifts and there is no play. I'm thinking there is no easy way to secure it other than setting it into a pair of v-blocks and welding it in the aligned position. Other than that option, the crank is now unusable. What a shame since the engine came out perfect otherwise. I could live with the click if it was just normal play, but as it is, this is going to wear the rod big end bearing.
Never expected to see this problem in a small engine. I now know I caused it and should have gripped the same end the adapter is mounted to. Maybe replacing the crank is the best option I have?

John