how to install head?
I have a friend (we will call him Bill, because that is his name) who owns a Newport 27 that he still owns after buying it new around the time you mention as the build year of your boat. Yes the tank is under the V-Birth. I think he had to replace the tank about two years ago. I am sure he can help you with all of the details of the installation, we no doubt could even take some pictures and send them to you via e-mail.
As I read your paragraph of questions, I have to believe that your boat was built with the Porta Potty option. For one thing if the factory did install the tank there would be a pump out fitting in the deck, which I am sure you would see, as well as the vent, which I think is just under the rub rail.
Bill lives about 5 blocks from me and I see him all the time. I will talk to him tomorrow, that will be Monday Jan. 23. To get this started you can drop me an e-mail -- firstname.lastname@example.org --.
Walt Ward - Northern Lower Michigan