Boy, can I identify with how you're feeling. Been there.
But when I bought my 1950 3600 2 years ago I did it because I wanted the "therapy" that goes along with a project of this type. When I began feeling disappointed in my progress I took a month off and thought about why I started it to begin with.
Then I decided I would work on it ONLY when I was in a good mood and had no family commitments breathing down my neck. Even if it meant only working on it once or twice a month.
It was the best decision I could have made. Now, when I work on my project I feel good about it and really enjoy it because there's no self-imposed deadlines making me feel guilty. And the project is taking shape just the way I envisioned it, with no shortcuts. I spent the last 2 years building a great engine and rebuilding the entire chassis/suspension. The engine is in and looks/runs beautifully. Now I'm working over the rust bucket cab, and enjoying every minute, and even looking forward to the next time I can spend time with ol "Therapy".
And I don't care if it ends up taking 5 years or more to complete. I realized the work is 80% of the fun of owning one of these great old trucks. Not to mention the pride in saying "I built this".
Just my 2 cents worth.
Good luck with your project!