No, Ruger doesn't make a 22/45 with a 10" bull barrel.
Also, while you might be able to buy, say, a 5.5" 22/45 and a 10" MkII and swap the top ends, selling the resulting 5.5" MkII and keeping the 10" 22/45, this is harder than it looks. I tried swapping tops between a 22/45 and a MkII and they didn't interchange very well. One was too tight and the other too loose.