Sounds like a lot of hear say going on. The only way to know is ck.
My 300sd blew a head gasket at 640,000 mi.Just plain old age,checked for straightness,
was good,cleaned up reinstalled,Using old head bolts,they did ck with-in specs.
Have repaired thousands of these Mercedes,stay with-in the specs,use common sense,
things well be good.