ldrofdpac

Hi, I bought my grandson a 78 280z. The body was very good. the motor had lots of blow by. I found a brand new motor that had sat for a while. when I got my motor out I found the exhaust ports on my engine were round and the new one was square. My old engine was as L28 my head was a N47. My new one had a P90 head. I was told that this was a turbo engine, with a lower compression ratio. Can I mill the head and get the compression retio back up.