I love the ruger old army. It's built just like the regular blackhawks as far as being tough and produces excellent accuracy. Stainless is the only way to go just in case you (as a beginner) forget how important cleaning is right after shooting due to corrisive nature of black powder or pyrodex.
The powder I switched to is american pioneer powder. It is not corrsive and has no fouling buildup. In cap and ball revolvers I use FFF grade.