
As far as the theme goes, that is a dilemma. Do you have more of the score, or is it just the track from "The Sea Hawk"? I don't hear anything in that track that would match very smoothly as the opening of the end credits, unfortunately. If you can make it work, though, that's fine. At the same time, I do now recall that John Williams had the Rebel Fanfare in the opening of the end credits of the PT, even though it didn't chronologically debut until ROTS, because, in the spirit of the "serial" feel they were going for, the end credits music remained a constant throughout the saga, tying it together in just that little touch. So even with the approach you're going for, I don't think it would be inappropriate to keep the end credits opening the same; it would simply be a matter of preference. Both ways have their merits.