These types of projects are rarely "worth the cost". People do it for the challenge and therapy. It's better than playing golf and might be cheaper than going to the strip clubs. Cheap, as in you're not going go through a divorce
The answer to your second question is ALWAYS going to be a YES! Leave your 80 alone and enjoy it for camping and wheeling then get a more economical transportation for going to work and such. You'll be money ahead as well as time. Remember, these projects eat up a LOT of time, which can be spent making memories with your family on trips.
Just my .02 cent