Here's a thought: with its bound headstock and F-holes, center-raised headstock, and ebony fretboard, you could say the Manhattan Special inhabits a place between an X-175 and an X-500. How much closer could you get? Guild has gold hardware, including gold DeArmond pickups, knobs, tuners, and a choice of gold Bigsby (for the Starfire VI) or gold harp tailpiece. If I'm not missing anything, the only remaining parts for a 50s-era X-500 would be the G-shield headstock emblem, and having an engraved tailpiece.
Guild already makes the G-shield for some of the USA acoustics, so if they wanted to create a 'modern vintage' X-500, all they would need to invest in are engraved harp tailpieces, correct? Its interesting to think about.
(P.S. Let me know if I'm missing anything in my thinking here.)