78 corvette

I have a 78 2-tone silver, 25 anniversary vette, that i
need to sell for my stepfather, he is the original
owner and ordered this car when he owned a
dealership. I was told it is one of the first  5000
produced. It has been garage kept, and is in
excellent condition. It has less than 28,000 miles,  
and is in original condition. Also we have all
original documentions.   
Any help with its value, and best  way or place to
sell would be greatly apprieciated.  
Thank you,
Chris