If the chain were off by one tooth the valve timing will be off about 16 to 18 degrees. Does that allow the pistons to hit the valves - I don't know.
A chain that's run 270,000 miles is very tired and suspect. The chain not only wears but also stretches. The rule for the old 3.0L 617.XXX five cylinder turbos is that the chain should be replaced if the crank shaft angle is 5 degrees (or more) when the camshaft is at 0 degrees.
The measurement is made on the 617.XXX engine by rotating the engine until the notch in the thrust collar that's immediately behind the chain sprocket of the cam is aligned with a groove cut into the first camshaft support's left side (0 degrees on the cam). One then reads the crank angle off the scale on the crankshaft's vibration damper (where the belt drive pulleys are located). Your engine may be a bit different but the principle will be the same. This check will also determine if the cam is correct or off by one tooth on its sprocket.
Finally, in closing, this engine is getting close to the mileage where it will need an overhaul so it may be worth considering, depending on the condition of the car, either doing a full overhaul, or doing nothing until it breaks and then making the decision to overhaul it, install a used engine or scrap the car.