Re: Updating electrical system
Congrats on the Pearson 39. They are great boats. (Are the decks sound?)
How do you plan to use her? Daysails and weekends require different a charging system than a live-aboard.
To begin, I suggest that you improve/stabilize what you have, before adding expensive wind and solar.
I have replaced the battery charger, and most of the wiring on my '87 O'day. They did not use tinned wire, or adhesive lined crimps back in the '80s. After that, I would add a galvanic isolator (probably none on your boat, as they were not required), and a negative bus. You may also want to add a higher output alternator.
Then, if you are not planning to live aboard, I would add a small solar panel with a MPPT solar charge controller to keep the batteries topped up.