Bob,
I'm with Raymond on this, I did not mean to sound too alarming about the pump. I just know that getting the arm back on properly is not a DIY job, it requires a specialist with special tools. And even though the list of other items you mention seems long enough, none of them are too bad. When you go to reinstall the pump just ask, there is no trick to it, one needs to be careful about the timing marks as they differ by type of pump (early or late). The tank and radiator will also require a shop familiar with these jobs, but not necessarily a Mercedes specialist. Every thing else is "plug and play" so DON'T GIVE UP. After all its an old car and, just like everything else, is subject to some failures over time.
BTW, my wife and I spent a delightful week in your City last fall, stayed with my daughter who was a student in Rome and stayed in her apartment on Piaza Navonna. I cherish the memories. The people, the food, the art. Just one question: do the cab drivers have some kind of exchange program with NYC? Yikes!
Best,
g
'64 230sl, fully sorted out...ooops, spoke too soon