Sounds like you know what it's going to take to pit it together and sounds like there are some good things going for it in spite of all it's going to need.
Chevelles aren't cheap, period.
So if you can get it under $1500 I'd say go for it, as long as you are willing to do what it's going to take to put it together.
That's going to be a great project for you and your son.
My 13-year old son and I are looking forward to getting the motor and interior in our 70 over this summer.