I bought a smaller buttplate from Brownells (the smallest generic one they had). I cut the stock off to the length I wanted with a chop saw, rough sanded the inside to make it grippier and added epoxy putty to replace the screw holes.Greased the buttplate and screws and installed while the epoxy putty was setting. Once set, remove the buttplate, remove the grease from the screws, and reinstall. Sand buttplate to fit the stock if you want -- it was close enough for me. Works great. This was based off someone else's instructions here on saiga-12.
If I can do it you can do it. Took about 1/2