I have a restored 68 SS350 Camaro that has a Mint Original GM factory Walnut Steering wheel, aftermarket hub and horn button. The wheel has no cracks, stress marks or scratches in the center. I have been slowly transforming the car towards ProTouring and since it is a NOM car (currently a 69' Corvette "512" block 427 / 390hp engine with a Vette 700R4, which might get pulled in favor of a LS engine swap, I am good friends with the guys at ATS -American Touring Spcialties)
So with the much improved steering, spindles, suspension, etc. The stock wheel doesn't "feel right".
What is the current market on the original GM Walnut Steering wheels ?

Good ones fetch around $500 these days. Wear on the grain at the 10 and 2 position and condition of the stainless spokes can knock it down a bit.