Possibly buying sr250, some questions first

I went to look at this bike today, and it seemed pretty clean and put together. It cranks over and the lights and starter work, and the gears shift pretty well. It has spark and compression. My question is this, If there is spark, that means the problem should be the fuel system right? Could there be anything wrong that is more expensive than a carb rebuild/replace?

http://losangeles.craigslist.org/sfv/mcy/5129623284.html

Most bikes that have sat just need a carb clean, mine did.

Cosworth, do you know how different the xt250 is from the sr250, is the frame completely different?

The xt frame is very different. It has a monoshock where most of the sr wiring would be. Also the xt motor has no starter and is shorter in length.