I don't think it's worth it. You can spend another $5k-$7k and get one with 100k on the clock. You could easily eat up $5000 with a new clutch, brakes, u-joints, ball joints, lift pump, CP3, injectors, water pump, shocks, driver's seat, a/c compressor, trans rebuild, power accessories, or any other items that can go wrong with such a mature truck.
On one hand, you might be getting a cared-for cream puff. On the other hand, it could be a disaster waiting to happen.
One thing you have to ask yourself-- Why are they getting rid of it at 270k? If they kept it that long, I would imagine they'd keep it longer if they thought it was a reliable rig. Something is compelling them to get rid of it.