That sight might be near impossible to find but good luck. However, I do see crescent butt plates turn up on eBay so you might want to keep an eye out on that sight. If you don't mind me asking, what sort of project you have going on there?
"The universal aptitude for ineptitude makes any human accomplishment an incredible miracle." John Stapp - "Stapp's Law" "Klaatu barada nikto"