I'd look for a used cylinder in 22 lr or 22 magnum. If it's a long rifle cylinder, a gunsmith would be able to ream it to 22 magnum for you for not too much money. Most of these cylinders are a drop in fit, and will be close enough not to cause problems for you. I tried a used New Model ACP cylinder in an Old Model 45 Colt that I had and it worked with no effort at fitting. It was accurate and fun to shoot. In fact, I kind of wish I'd held onto the cylinder when I resold the revolver since they're kind of hard to find. As long as the cylinder indexes properly when you work the action and doesn't spit through the cylinder gap when you shoot it, you'll be fine.
