Honda sell the XRR with 14T front sprocket in some countries and 15T in others. a good dealer should be able to trace the 15T sprocket for you - get a couple! I can probably find the part number for you if you're stumped. I got my sprockets from Dave Silver in the UK - top service and 20% off if you can wait a few weeks. personally, I'd use Renthal bars, but not sprockets. Honda stuff is expensive and worth it ie its usually excellent quality. similarly, I'd get a spare Honda filter as it comes pre-oiled in a sensible size bag.

XRL v XRR. if you search the Honda forum you'll find loads of commentary on the pros and cons. neither bike is "right", but I'm not sure any bike is "right". I've done trips through Africa on both the XRL and XRR. both are reliable and both are more than adequate off-road. neither is really comfortable for hundreds of kilometres, but, given enough effort, both can carry 40-50 litres of fuel and 15 litres of water across sand and rougn terrain.

I've not been to south america so I don't know about the roads or distances between fuel stops. if I was mostly sticking to the road/gravel, the XRL with 22 litre tank is straightforward. if I was going to do the Baja, the XRR with 28 litre IMS, would be my starting point. or maybe that F650GS project bike that I haven't started yet ...