A chassis of that vintage, with working brakes, is worth around $500-600. The Rotax would need to be brought to current specs, and have passport, etc., probably a $600 process. The engine is worth around $800-1000 as it sets.... If you can get the package for $1500, probably worth it. For someone new to sprint karting, this would be a great package to start with if everything works and the bottom of the chassis doesn't have bad flat spotting.
I'm setting up a mid 90's chassis now for KT-100 Yamaha racing, and just got an almost complete 2012 Intrepid chassis. If you're interested in the Intrepid, I can make you a deal.
PS - there's a little tag welded onto the rear crossbar that you can just see in the top pic. It's near the bracket for the water pump. If you can get a pic of that and post it, we can tell you more about the kart...