FWIW, I am going to leave my vintage Charleston in the dash, but have it run into a Soundstream ST4.1000DB amp I will install under the passenger seat (4-channels @ 90W RMS). The cool think about the amp, though, is that is has Bluetooth for connection directly to mobile devices. This way, I can have an original look, plus updated sound (I already updated the speakers), along with verstility for mobile tunes. I just ordered, so will report back after i receive it and do the install.
Soundstream ST4.1000DB 4-channel marine/powersports amplifier with Bluetooth® — 90 watts RMS x 4 at Crutchfield.com