Advice and things to know about buying a 1991 Nissan 240SX (5speed)

I am interested in buying a 240SX near where I live and I was wondering if anybody has some good tech advice. The car has 274k miles on it, the front seats are worn out and it has a head gasket leak. The female owner has left the car completely stock other than intake. The bodywork is solid and the paint is flawless. If I can get the car cheap, I was thinking the SR20DET swap might be a good way to go. Any advice would be appreciated, thanks!  
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Rev, shift, smile, repeat as needed.

Although I am probably late in the reply for you, perhaps this will help some others.

First, the 240sx is one of the best import platforms ever to grace these shores.  It has a very advanced rear suspension, and decent front suspension, and enough aftermarket support that the few shortcomings in the handling can be easily overcome.  Having said that, keep in mind that it is a larger car than many other imports of that era, and some body lean can be expected.  Although its turning radius is very small (useful if you have to park in tight places common in urban areas), sometimes visibility from the driver's c-pillar is problematic.  

Depending on where you live and how you drive, the FR platform can be a blessing or a curse.  It is tail happy, especially in wet conditions.  If you live in the far north where snow is common, this is probably not the car for you.  Complicating the tail-happiness of the platform is the short gearing and torquey motor.  As you may know, the KA24DE that came in the '91 is basically a truck motor, and is not mean to rev high.  On the other hand, it has a very good torque curve that makes it a pleasure to drive in dry weather.  The short gearing does mean that you can expect to make a lot of gear changes in around-town driving, and you will be revving fairly high for an engine this size on interstate driving (3400ish RPM at 80 mph).

The engine itself is very solid and reliable.  Replacing a head gasket took me about 8 hours the first time, less than three the second time.  Replacement parts are cheap and plentiful.  The undersquare engine setup does tend to wear the rings: the best way to check for oil burning is have the car start cold and observe the color of the smoke.  Blue means its burning oil and that the rings could be on the way out.  White means fuel or condensation, and you are probably in the clear.  The if the shocks are still stock, be sure to do a bounce test (push on a bumper and make sure the car comes to a stop within one oscillation upon release).  I can't really think of too many other things that are known to be problematic or that I have had trouble with.

My background has been very positive.  I bought a '91 240sx with minor body damage and a twitchy MAF.  I rebuilt the engine with low compression pistons, forged rods, and turbocharged the KA.  I'm putting out about 275 HP at the crank while maintaining drivability.  

Oh...and as for the front seats: be careful if you buy "race seat" replacements.  The seat rails on the 240sx are kinda funky, so be sure you buy your rails from a reputable dealer or you may end up with living room furniture that you can't mount in your car.

If you are looking for a very knowledgeable community that is always happy to give helpful advice, check out NICO Club online.  

Good luck.

RY