Hey brodg, it doesn't look too bad from the photos, but looks can definitely deceive. As to whether or not it's "worth it", that decision is really up to you and your dad. There's a value on doing a project together like that and it can't be expressed in dollars and cents. A lot will depend on what it needs and also what you want it to be when you get done. Taking it back to "mostly stock" is one thing, going the "resto-mod" route where you do things like upgrade the suspension, brakes, drivetrain, and engine is going to be more expensive.
It's almost always cheaper in the long run to buy a car that's "ready to go" than it is to restore one, but then you won't have the opportunity to share the build project with your dad if you go that way.
A good, near show-quality paint job is going to set you back more than $10,000 easily, not including the body work beforehand to get it ready. That's because it's all in the labor before and after spraying --- the actual application of the finish itself isn't all that much.
If you want to build a strong engine, say a stroker with good parts, you're going to spend that much or more again.
And we haven't talked about suspension, trans, rear axle, and interior yet...
I'm not trying to talk you out of it. In fact I think a father-son project like this is one of the coolest and most rewarding things you can do. Just be aware going into it that it's going to cost a lot in terms of both time and money invested. That's important because just like finshing a project like this is very rewarding, starting it and then NOT being able to finish can be one of the most depressing/defeating things you can experience.
I'm pulling for you both.