I have to agree with most of the others. 2520's are still in good demand as both working tractors and as collector tractors. In good original condition, they can sell for as much as a side console 4020. If your tractor is running, you could probably sell it and then buy or build a different pulling tractor with no money out of your pocket.
It does depend on which class and weight you want to pull in. It's your tractor, you can do what you want with it.