'66 Chevelle SS Convertible Red w/White Leather upholstery ... 17K original, cherry in garage ... 327 3 carbs, 3-spd Hurst ...dual chrome side exhaust ... Inherited by my friend from her dad the original owner, she held on to it for sentimental reasons, now will sell ... Any advice please on possible value and appropriate buyer for this classic, or where else to inquire.... Thanks  

If it is cherry and does in fact have 17k miles, I woudn't let go of it for less than $12,000. Actually I wouldn't let it go at all but I'm a sentimental bastard.
Look on Ebay to approximate a value for it, or for that matter, put it on Ebay with the reserve set high enough not to get burned and go fishing for a while.  

This doesn't pass the smell test.  '66 Chevelle SS were available with only a 396ci big-block engine.  Small-blocks (e.g.; 327ci) were not available in SS trim in '66 models.  

Edit: You either have a clone, or some knucklehead swapped motors (which will depreciate its value).