There's two ways of determining the value of something.
From economics: What a willing buyer will pay a willing seller.
From experience: What it would cost you to replace it with something of comparable worth to YOU.
Note that the second definition is much more subjective -- the worth to you can be influenced by what your needs are, how you think it looks, how you think YOU look in it, whether it has sentimental value, etc.
By the first definition, I don't think it will be worth it. The replacement parts and your time will not make the truck more valuable than the cost of the parts and your time.
By the second definition -- the only one who knows is you. Do you LIKE the truck? Do you like working on old trucks? What are you going to do with the truck? As far as trucks go, it's a very rugged and bulletproof design. But it IS still 41 years old! You should expect to have to perform a LOT of overlooked maintenance. With my 60, for instance, I'm basically assuming that everything has to be touched. I'm planning on having a like-new truck.
Have fun!
Brian
