Check the compression, it's either there or it isn't.
Assuming you'll be using it as a daily driver, be sure to replace the fluids ASAP, including flushing the radiator. The rotaries tend to overheat, and a new radiator and water pump is cheap insurance for the old motor.
If you'll be running it hard, you can add 1oz of 2-stroke oil per-gallon of gas in the gas tank. This will supplement the oiling of the apex seals under extreme conditions. Don't do this if you still have the catilitic (sp) converter still installed.
If you are in California (or similar state), be sure to have the current owner have the car 'smogged' before you buy it. The rotaries are not easy to get past the emissions test.
