If the 500 was to big for size/performance in your smaller room, then why not look at one of the other smaller Axiom Subs, then your finish would match your 60's.

M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85