Where can I get a wooden stock for a CZ550 in 458 Lott. Tried CZUSA and they don't have any.

I would try AHR, they probably have dozens of take off's.... Or even make one for you..

I have one from a Lott. It came to me in a package of Lott bullets, brass, and dies. The checkering is atrocious, but salvageable with a bit of re cutting.
Let me know if interested. All factory, I believe.
Stephen