If your sprockets are fairly new, they can be reversed so that they are running on the unworn side. You slide them off the end of the top feederhouse shaft and slide them back on the opposite way. That'll save a few bucks. If they are partly worn on both sides, you may as well change them for how much they cost and how much wear they can cause the chain. As for feeder chains, stick with the factory ones that are riveted. The problem with bolted together ones is that the workers putting them together with impact wrenches usually over-tourque a few, crack the bolt and you get a slat coming loose. Riveted ones are really strong, especially if you take in a rock. If you have one come loose, then bolt in a replacement.