UPDATE:
I wanted to report my steering wheel restoration results for future reference to other members considering the same work.
My wheel was in 50 year old condition- you'd get black stuff on your hands if you rubbed it too hard, lots of cracks, discoloration, etc. I took a triangular file and opened the cracks, then filled them with epoxy putty. Afterward, I sanded the whole thing down with 220, followed by a solvent wipe. I used the SEM products sold by Eastwood company (cleaner, Sand Free, and high elongation Landau Black paint) and coated the steering wheel.
I'm VERY pleased with the appearance of the color. The shade and texture seem spot-on. I'm rather disappointed with my sanding ability. You can see the ghost of the fills because I didn't fair the epoxy out very well at all. Can't blame Eastwood/SEM for that. My bad.
No word on toughness until next January and a few Januarys after that. But for now, I recommend the products, and strongly urge anyone else considering this to be meticulous with their sanding. It isn't easy sanding a very hard epoxy fill so that it blends into the softer parent material.
My SEM products were a gift- I look at this as "practice" and a spruce-up. Can't call the results of my effort a restoration!
Bill