Marine engines and car engines are different internally . All if the clearances are different for marine application. Rod and main bearing clearance is larger for marine use. Also piston to wall and ring end gap are different . It makes a big difference if you want an engine to live in a marine application .
A 97 Merc 7.4LX and a 97 7.4 GM truck engine (both TBI) run the same clearances according to their shop manuals. I am certain this is an exception. These engines do not make much power at all. When it comes to making big HP the clearance are definitely different.
