looking at a TSi

i have some people interested in buying my 89 240sx. i can probably get about 1500 out of it. a kid in town is selling his Talon for about a grand, he basically said, "whoever can give me cash first"...so i can probably get it for 800 bucks. one problem though, the rings are shot. it smokes like a factory. i figure i can rebuild the motor for the rest of the 700 or so bucks i will have after i sell my car, but i have never even taken off the valve cover before. so i know nothing about the guts of a motor. how hard is it to rebuild this particular motor?? btw, what is the engine code on this motor? mine is ka24e... do you think i can rebuild this motor for around 500-700 bucks??

thanks in advance,

paul