10/22 SBR project, using a Choate folding stock.  The front and grip swivels will go away.  



Using this push button swivel:





Where would one find a female half that could be mounted to the plate, replacing the pictured swivel?:




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I think you could just use one of the ball lock swivels and carefully drill/ream the hole to the proper dimension. Or worst case, install a modified female uncle miks swivel cup, a little TIG work & modification on the cup might be required but I know someone that can do that

http://www.brownells.com/aspx/NS/store/ProductDetail.aspx?p=8892&title=UNCLE%20MIKE'S%20QD%20100%20SLING%20SWIVEL

No good way IMO.  Use a MASH hook adapter and clip it to the current swivel.

CS, that's exactly what I was looking for - these will work great.  I like the idea of using the plate but accessing the underside to ream it may be problematic.  
The plan now is to also add one of the cups to the underside of the grip - that allows a 2-point attachment instead of just a single.  These provide a cleaner look too, when the sling isn't in place.  
We can make it work.  Thanks.
From the Brownell's link above:

eta:  For others future reference, just noticed that Blackhawk sells these too:  


http://www.blackhawk.com/product/Push-Button-Detachable,477,115.htm