Heller's Le Phenix

  While I'm not familiar with this particular ship, I can tell you that during this period ships were often repainted according to the wishes of the current Captain, or even according to what paint was available at that place and time. I would try to match something from that period though, and not use colors that they probably wouldn't have had. True "gold leaf" was usually found only on certain ships, and then only if the Captain or the government was willing to lay out the money to keep it on there. Also you must keep the white lower hull since that was part of the "anti-fouling" material used at that time and was always white. Hope this helps.

The older the ship the more likely the paint instructions are based on speculation.  By the Eighteenth Century the governments/admiralties and the like controlled the main colors pretty well by standard. But with earlier ones, you can be as speculative as anyone, though still historical research may be possible to determine what colors may have been used.

How accurately you follow the instructions for later ships depends on whether you are making an accurate scale reproduction.  One time I did a Constitution for my father and he wanted it painted more colorful than the real black and white, so, while I am ordinarily a believer in fidelity to scale, I followed his wishes on that one.

This ship is a complicated subject and, since I'm not really knowledgeable about French naval architecture, I'll refrain from offering an opinion on how the real vessel was painted.  But I will say I'm a little bit troubled by the original post.  I'm deeply uncomfortable with the use of phrases like "do I have to" in the context of model building.  For most of us, this is a hobby - and there are no "have to's" involved in it.  It's your model; there's no police force waiting to bash down your door if you use a "wrong" color.  Sailing ship modeling, in fact, leaves room, even within the boundaries of historical accuracy, for plenty of personal taste.  May that always be so.

And furthermore,that is a really large and complicated model, one I started a long while back and abandoned because it was way too difficult. If you were to finish her, even just to the level of the thwarts, it would be quite an accomplishment, like a La Reale completed here recently.

I have heard, and once had some luck, contacting the French National Maritime Museum. In my experience, contacting museums is somewhat delicate, but successful if you are focused about what you want.

Remember though it's a fictional ship, so you'll have to work around to what your real question might be,

http://en.wikipedia.org/wiki/Mus%C3%A9e_national_de_la_Marine

And on the general subject, any of the books by Jean Boudriot are great to look at.