Ragstone Models (Andy Beaton) now have a 7mm scale GCR buffer stop available. It looks extremely good. A much-needed addition, and much more accurate than even the best modified PECO version! I shall be buying some at Telford.
The above photo shows the prototype.
This is the model.
(Photos courtesy A. Beaton.)
EDIT - Having got my mitts on three of these at Telford I can assure you all that they are every bit as good as they look and well worth the price of £10.