The shooter is almost always more important than the gun. If you are up to the task, a .22WMR in your hands is probably more effective than the Browning HP in .40S&W that I watched two "yoots" in gang attire shooting a few years ago. Many of their shots were missing the entire (large) target at 7 yards.
Back on topic, I would find a good solid point WMR round and run at least 200 of them through the gun to make sure that you have no problems with ignition, and that you can shoot well with your chosen ammo. I'd also buy at least 1,000 rounds of .22LR (bulk packs) and practice, practice, practice. Get some instruction, if you can, or at least some coaching. Be 100% confident in that Single Six, because you shoot it regularly and it comes in line with the target like a living extension of your body. Regular, good practice will also make you safer with the gun. There's gotta be a Cowboy Action shooting club nearby, and perhaps they might help you learn to load, unload, and handle the revolver smoothly and safely. Some of the CAS shooters are good enough with a single action revolver to give shooters with more modern pistols a run for their money, at least for the first 5 shots, and that's more than most people ever need to fend off an attacker.
You can "load" empties into the cylinder for "free" practice. Rimfire pistols shouldn't be dry-fired, but if you load an empty with an undented area of the rim where the hammer will strike, that should prevent harm to the gun. Make sure you keep a "fresh" part of the rim under the hammer for each "shot," to protect the gun.
If you're good with it, that Single Six should serve you well until you can get something that will tilt the odds even further in your favor.
All my best,
Dirty Bob