I thought I would put in my .02 ,,,
my thoughts are it needs to be running , if it is at least running to where someone could hear the motor that will make a huge difference in price as to what you will get for it in the end, doesn't really need to go down the road just fire up and idle.
if you are going to put it on craigslist to try and sell take advantage of ALL 24 pics they let you put on there, remember a picture is worth a thousand words or maybe another few thousand $$$
what its worth is another story, there are 57's on fleabay but you have to save the auction and see what the end bid was, don't go by what they are asking, go by what the final bid or sell price was then you have a start to what to ask, I haven't had a 57 in a long long time, so I couldn't tell you what to ask, most likely you wont get what you put in it , but I will say the cleaner it is and the better it runs you will get more , hope this helps, Jim