Overheating '68 280SL

Do 280SLs have any unusual overheating issues? I have a '68 280SL - very well tuned and running right, except temp gauge climbs fairly steadily, even in 65-70 degree weather. I am certain that brakes aren't dragging and radiator is clean. Any ideas on things to check or solutions? I am suspicious that the very low mileage of the past 10 years may have lead to corrosion or settleing of sediment in cooling passages - any suggestions for flushing or cleaning cooling system?

Thanks in advance.

This M.B. has been known to run hot, and even more so with a/c. Try flushing the cooling system & replacing the thermostat. Mercedes sells a cooling system flush w/citric acid. Head gaskets have been known to cause this problem.

Just a suggestion, try putting in RedLine
Water Wetter. It will help the cooling by 15-30 degrees. This stuff works and for only about $6-7 a shot. No harm tried.