I believe the orginal looked like this:

You can get a replacement that looks like it, but with some updated features.  Here's the one Mid America is selling, and probably the other Corvette parts dealers as well:

http://www.mamotorworks.com/corvette- ... -upgrade-1-307-11234.html

And another:  http://radiosrepro.com/1971-1972-1973 ... 1975-1976-corvette-radio/

Custom Autosound and RetroSound both offer "classic look" radios, but they are definitely not going to pass for orginals:

I'm not a stereo guy, so I can't really make any recommendations.  Maybe somebody else can chime in.