My FIL pulled a 3 yd "Michigan" behind an old 3020 with great success. He removed the dolly and set the tongue of the scraper directly on the draw bar to gain traction and he had a real "go get her" machine. His 3020 had wide grove tires and he was working FL sand. It was a great combination. :thumbsup:
Your tractor should do fine. If you don't have rear ballast, I would strongly suggest it. Fluid filled tires or wheel weights, or both. Without ballast, you probably will be spinning your tires a lot. That's hard on the rear end, as well as the tires.
We used to pull a 5 yd with a JD 4630 which was rated at 160 hp. I don't think you would have any problem pulling it with a 3020. I love those old 20 series JD's. They are popular for a reason!!