Have been down this road on two 240D's, a 76 and a 78. Neither one bent valves and the pistons were fine on both. Both broke the camshaft towers.

The piston in the last picture shows a lot of pitting, more than I would say is ok. The scratch on the cylinder is also concerning.

How did it run before the chain broke?

Can you post better pictures of each piston?

Did your towers snap?

I don't know why the chain broke on the 76 as I bought it that way. The chain broke on the 78 because the front main bearing failed: thereby, stopping oil flow to the chain and it snapped. The bearing failed because I had the bearing fitted too tightly.

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer