I have a custom stock for a M660 that I would like to sell. I did a search and happened to see your inquiry. It's a Gary Goudy Classic stock design made by Great American Gunstocks. It has an ebony forend tip and ebony grip cap with a 13.5" LOP.
The stock is in excellent condition. I paid $650 for it several years ago and I'm looking to get $350 for it.
I don't know how to post pics here, but I can email you pics if you are interested.