I am not sure you can buy a grip frame from Ruger direct. Brownells used to have them, but they have shown them out of stock for several years. You aslo need a different hammer and trigger as well as some different scews to do the conversion.

Unless you are willing to wait like for ever the only way to do it is to buy a regular Stainless Bisley Blackhawk or Vaquero and exchange the parts. That may be 14cm's best option since he already has a 45 Hunter.

Actually that would be the cheapest option since you could the sell the other gun at a much less loss than the cost of the Bisley parts.