value of 67 convertible

I must first admit that I know very little about 'stangs, but my landlord knows even less. He is offering for me to research, detail, and sell his 67 convertible for him for a commission. He knows I'm a car guy, but those of you who know me... I'm a $300 car guy, not a $10,000 car guy.

Here is what I know:

-67 convertible, kinda teal green, black top in good shape
-289 2V V8, as far as we know original
-Automatic
-teal green interior
-somewhere around 100-120k miles
-fresh paint that is darn near flawless, but the back right fender has a blemish/dent.
-A/C
-manual 4 wheel drums
-he said it runs but poorly. I'm going to look at it this weekend and see what I can come up with. I heard it run when he brought it in and it sounded like a simple carb issue, but... factor that in.

The interior is very nice, no rips or sun damage. I personally think its a survivor car with the exception of recent paint and aftermarket wheels. If I have time tomorrow I'll take photos and look at the ID plate.

I looked on NADA and they came up with anything from $13,000 to $36,000. Not only is that seemingly optimistic, its a huge spread.

Any thoughts on its value?

Thanks