Ok, I shouldn't say this BUT........
I have a '74 280 with a twin cam engine. I put a red coil in it a few years ago without changing anything else and it's still running. This system which is CD ignition like a late 280SL, may not be exactly the same.
I had a lot of problems with rich running and poor starting which the hotter coil more or less cured. It is, after all, an engine noted for all kinds of carb problems.
Dan Caron's
SL Barn
benzbarn@ebtech.net
slbarn.mbz.org