Best of luck. Chambers list them, but I've never seen them shown as actually in stock.
At the risk of stating the obvious, have you googled 'CP88 wood grips'. When I was looking, I did so, and you'll find quite a few threads including a couple where IIRC people were making them, possibly to sell on.
I also think there may be a German company doing them. I'll see if I can find their details. I opted not to fit them in the end as mine's nickel and I think I prefer the black grips.
AA S400 carbine in .177 Walnut stock, Rowan multi shot conversion, Rowan trigger, Huggett mod. MTC Mamba 3-12 x 44.
Refurbished 1986 BSA Supersport .22 with MWSS custom silencer.