$1500 for a new 84" rake, yikes! $5000 for a power rake, double yikes!! Actually, I knew the power rake is priced where it really only makes sense for a commercial user. As for the manual York style rake, if its short term to finish one project don't overlook the possibilty of renting one. I'm guessing maybe $100 per day. Sizewise, 72'' is perfect for the 2520 and the 84" is also probably fine for spreading loose material. If you might have more use for it in the future do seriously consider the used market. There's no motor, gears, etc to go bad so as long as you find one straight, not broke, and not missing any parts it will work just as good as a new one. Basically what you see is what you get. I found a used Woods 60" box blade (with scarifiers) and 72" rake (no wheels) together for $800, both in excellent condition, to use with my old 755 and now my 2520.
The box blade works excellent on undisturbed ground and the rake is good (with practice and patience) for spreading loose soil/stone or removing rocks and debris. For final grading it will (with or without wheels) tend to follow the existing contour of the ground you're working. You'll want to go slow and have your right hand on the 3PT lever at all times to knock down the high spots. For final smoothing out of loose dirt and topsoil I bought a $150, 4x4 foot drag harrow from Tractor Supply and it works excellent. For this final step I drag it upside down behind my small 455 (with turf tires). The 2520 should easily handle one of the bigger versions.
Good luck with your project.