I have twin NA 7.3 IDI engines in my 21000lb boat. I run them at 2500 rpm all day long.

My compression test was 360,410,450,440,400,390,390,360

A coupla were a little low but these engines have 3500 hours on them. I expect them to last 5000 hours.

I have been working on the idea of adding turbo chargers to the engines and should have the project operational by next month. I will post pictures when I have it set up.