The OM603 is an interference engine. There's a good chance of bent valves. The engine has to come out or be lifted to replace the main oil pan (if that's where the hole is) so there's little point in not pulling the head to do a good job of it. You can replace the chain then do a leakdown test but that's a lot of work and cost up front with a $1000+ variable of rebuilding the head hanging in the balance.

Sixto
95 S420
91 300SE
87 300SDL
83 300SD