Get a used engine oil lab analysis. If that comes back clean, buy it.

A replacement head probably was installed with the improved head gasket, which is strengthened at the oil passage near cylinder #1. Failure of that oil passage allows oil into #1 which hydro-locks and bends the rod, and then the engine is toast. If you can confirm this, and the lab analysis doesn't show abnormal levels of metals, the engine is probably sound.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC