Anyone know of a source, or a generic that will fit (5" long, 1 5/8" wide, holes 3 3/16", curved). This is for a period Czech fullstock Brno.

I have used a number of the reproduction and universal buttplate and found them very satisfactory. I’ve heated them both in hot water and used my heat gun to fit them to curved surfaces. Find one that close to your needs. You can get exact measurements and even templates from this site.

https://gungrip.com/universal-butt-plates.aspx