Interlux has a gel coat / paint brochure which has paint chip samples of all of their available colors. Look for it at West marine. I would definitely try to match up a paint chart before spending A LOT of money for hull paint. But you will never match a 30 year old hull's original chalky hull color, with all of the fading, corrosion, oxidation, etc. thst it has endured.
So you will likely have to repaint the entire hull for a uniform appearance. So my advice is buy whatever color you like, because you're going to pay a lot for enough Interlux paint to cover the entire hull. Personally, if I were going to go to the trouble to repaint a hull, which I wouldn't because a good scratch or to makes it look like crap, I would go with a royal blue. Those old classic sailboats repainted in deep blue with a gold boot stripe always look like a million bucks. But every time I've asked the owner what it cost, the number ten grand comes to mind for the paint & labor. Ouch.