Pre68Dave's Blog (
http://chev235guy.blogspot.com/ ) is what you were thinking. Its important you don't use a 216 distributor in a new style 235/261 engine. The metals are different. Not sure if that causes wobble.
If you run your distributor in a normal shop drill below the gear, you can see clearly what is happening with your distributor. If it wobbles at all, it's the shaft. If everything runs true, then you can suspect maybe a bad cam gear, OR a worn cam bearing set which would also cause this.
Steve has good advice above. Its very important that you have that fiber or nylon cap that rubs against the shaft with the spring providing pressure.
