My 1987 190E started making chain noise at approximately the same mileage. Tried oil stabilizers to keep the chain oiled to prevent dry start up,worked for three weeks out of every month for the next 10,000 miles.
250,000 miles is the most to expect from a 2.3 gas even with extreme care,i would recommend a differntial cylinder pressure test to determin the condition of the rings,and a oil usage check,how many miles per quart of oil. Why? Because the proper way to do the guide replacement and gears includes removing the head (to prevent leaks) the oil pan and the chain cover,therefore you should do the rings,mains and rod bearings also.
If you intend to keep the car much longer you are already close to excessive oil burning territory,woul'nt want to go back into the motor in another 10,000 miles.