Itr is always dangerous to answer a question when the caliber is described with two digits, instead of three. YOU HAVE TO ACTUALLY MEASURE the Bore of the barrel of your gun and find out what the actual dimension is, before buying balls, jags, etc. IF the bore is actually .750 it is closer to being a 11 gauge( .751, nominally) than a 12 gauge. Your bore may, however, be smaller.
Circle Fly makes wads, and OS cards for all the gauges so you can pick up those supplies from them directly, or from the other suppliers named. If you go to the MEMBER RESOURCES section at the top of the Index to this forum, then scroll down to "articles, Charts, and Links", click on Links and it will give you a long list of suppliers. Click on their names and that will take you to their websites and catalogs. You can shop on-line. That is the fast way to discover most of the larger suppliers in this business.
You need both the ramrod that comes with the gun, and a " RANGE ROD", or Cleaning rod. We recommend a separate full length, metal rod, made of brass, or stainless steel for this work. It should have a good handle, and jags for all problems. That includes ball pullers, patch pullers, bronze brushes, swabs, and cleaning jags. The cleaning jag will be small in diameter than the loading jag on your ramrod. The reason for this is that you want a soft, light, cotton or linen cleaning patch to slide down the bore, over the crud, and when the jag is pulled backwards, to remove it and the patch from the barrel, the grooves in the jag grab the cleaning patch, and pull the crud OUT OF THE BARREL, rather than pushing it down into the breech. A loading jag can be concave, for loading a RB without marring it, but a cleaning jag will have a flat face, so you can get down to the breechplug to clean it out. The handle on the cleaning or range rod should be stout enough that you can turn a tight fitting patch or brush with it to reverse the direction of the bristles, or the fabric, to help it release from the bore so you can pull it out. There are several suppliers that will make you a Range rod to the length you specify. October Country, and Cain's come to mind. Dixie, too. you also want a muzzle protector on that rod to center the rod in the barrel, and protect the muzzle from the rod rubbing against it as its drawn out of the barrel.
Please don't hesitate to ask questions before you spend money on anything. We have all been there, and some of us were foolish enough not to ask, and we have spent lots of money on stuff that we didn't need, or won't work. Its part of the learning curve, but it doesn't have to be. All you have to do is ask. :hatsoff: