When I built Frankenstein, my parts 870, I was given a beatup stock that had been at the Md Pen. Ugly but functional.
I spray painted it flat black. looks a lot better now. Since the pressed checkering is roached, I may put some skateboard tape on the grip for better traction.
New utility grade 870 stocks aren't all that expensive, including the synthetics. And, check at your local LE oriented gun shop, there's often old ones there that might work for you, available at a pittance.