There are several things you can do. I live in Las Vegas, I will be trying many the same ideas on my 1977.

The aluminum 560SL radiator will bolt up and provide better cooling than the brass radiator. Or you can get much better radiator cores with more fins, thicker cores etc.

Clean the entire water system with a good cleaner to get rid of 40 years of scale. The citric type of cleaners are approved by MB. I just did mine with zero issues. Remember you can have the radiator boiled out, but if you replace the water system rubber hoses you will find scale on every surface, aluminum and steel.

Use "Water Wetter" or other type of water conditioners for better heat transfer.

There are many electric fans that will provide as much or more than the factory mechanical fan. Yes you will probably need to upgrade the alternator, easy!

There are several articles about using a Volvo electric fan. Also releases 5-6 HP the mechanical fan used.

Your exhaust manifolds can be wrapped with header - exhaust tapes, try Cool It Thermo Tec