Just a word of warning - the 9mm version can only safely shoot jacketed bullets, as per Ruger, in the owners manual. The use of cast 9mm bullets it not recommended in the convertable 9mm cyclinder.
Id get the 45LC/45ACP version if it were me. As long as its not a flatop version - that set up will be highly versitle!
The 45 Colt in Ruger Blackhawks, have their own load data in my reloading manuals, that will safely hotrod the 45colt, well beyond the 357 mag, and pushing it closer to 44 magnum territory. In fact many of the 45 colt Ruger loads, score a higher Taylor Knockout rating then the 44Mag, with less recoil!
Of course you can shoot standard cowboy loads, powder puffloads, or even the 45 colt defense loads that is prevalent on the market.
There 45ACP cylinder, can also fire the 45ACP+P all day long as well as some heavier loadings, that would not be ideal for a semiauto.
Here is an intresting article on some 45ACP loads for the Blackhawks:
http://www.handloads.com/articles/default.asp?id=41
I bought a Stainless Blackhawk Bisley 45colt/ 45acp convertable a few years back, its one of my favorite guns to load for, and shoot. Does a number on whitetails too!