Block mounted oil cooler lines.
 

I was thinking of using the oil cooler mount line located on the bottom of the block but saw a post saying those aren’t used in marine application? Are those too small or are they ok to use?

Guess the reason for not using the block access oil cooler mounts is not all the oil is directed through those ports. There’s enough flow to keep up with an automotive oil cooler but not enough for marine applications.