When I found him a perfect LHD 403 on offer for half its market value, in thanks Mark Wallach gave me a custom Rolls Royce steering wheel he had made as a proposed prototype for them (they rejected it as too expensive). Wallach was a renown classic car woodworker in New York. What was notable was the fact that the Rolls Royce spline fit the Bristol perfectly. All that needs changing is the leather boss below the wheel as the RR has a wider diameter due to how the horn button is made. You can see this in the photo.
Not knowing what the market is for used RR steering wheels, finding a RR wheel may be a no-go, or it may be a viable alternative.
Here is the Mark Wallach wheel. The deerskin leather needs replacing, but the wood is good.
http://quick.village-town.com/411.jpg
Claude