Sounds like it's running great.
One thought jumped to mind because I have a slip spreadsheet in front of me. Prop pitch specs aren't always terribly precise, but if your 25s are pretty close to 25, 5200RPM/1.5 ratio/80 mph would require 2.5% slip I think. Which seems pretty low. Not to say 80mph is out of reach, sounds to me like it is within reach with the coming bottom work. But I'd think it will come at slightly higher RPM or pitch. But again, just taking my best guess. Interested to hear how the 25s run.
Major congrats on your repower--really like that engine package you picked.
Mike
"I don't have time to get into it, but he went through a lot." -Pulp Fiction