I have taken my 87 300TD up a prolonged 18% grade with AC on and car under full throttle in second gear. The temp went to 110 deg C. This is after a recent valve job, new radiator, tpsta, fan clutch, oil-cooler and hoses. It did level off at about 110 but then I backed down. If you search for a thread I started a while ago, and read through it, you will get a good understanding of the operating temp on these engines. I did the search try this.
http://www.peachparts.com/shopforum/showthread.php?threadid=33994