Hello,
I have a 230sl with a 250 engine in it. I have the car for driving (original intent from MB, I think), and it is a nice upgrade. The only negative I have heard about the 280 is that the cylinder walls are somewhat thin relative to the 250 - hopefully will not be an issue for you. You have more main bearings and more power/torque than the baseline 230SL engine - only an issue for the purist I think....
Regards -- Roger