A car is worth to you, not what it's worth to anyone els, what you see it's worth. If you choose to spend the money then it means the car is worth it to you. You should decide to either keep it or get rid of it. I know this much. It would definitely be a sin to let it sit there and rot.
If you don't know, or are unsure on weather you should sell it or keep it. That tells me you love it and want to keep it. Learn how to do most of the work yourself and you can save a lot of money. You will appreciate the car more and it will be worth much more to you, when you complete the hardest tasks, than you can ever imagine.
I feel like this about any car I work on that's my own. I don't care what people think. It's worth more to me than anyone. Decide. You will not be disappointed with your decision. I can guarantee it.