There are simple Hershey kiss spinners that plop onto the aft crush plate, 6" is likely the right size for an O-200 crush plate. Chris Wade sold them and was lost in a Cessna accident - his son has taken over the fabrication - get in touch for more details. There are the earlier designs that go to the front of the prop, with prop cut outs...with the most sophisticated now offered by James Redmon, but may not be right for 6" crush plate...the only sure thing is that aluminum spinners can fail and cause all manner of problems...
Beagle canardfinder At Att.net