I would leave it as is. No professional of which I am aware does a proper vintage-accurate AUC ("poly") restoration finish. Everyone I've spoken to who does restos focuses on nitro only (even when the original finish should be acrylic lacquer or AUC), and if they are willing to do it in urethane, it's the modern stuff, which is bulletproof compared to the stuff Fender used in the '70s. If you aren't going to go vintage accurate with the refin, and you like the way it looks, then you shouldn't bother IMO. One day, when it's worth a lot more, a proper refin might be worth it, and then you won't have to strip off whatever you do now.
That said, bursts back then were nitro color coats with poly clear over them. Not as difficult to find someone able to do that...though the old style of less durable poly that Fender used is still something I've been unable to pin down in my [admittedly limited] research.