I maintain my gravel driveway with a box blade. It's a relatively short gravel drive. I don't think a box blade is very good at putting a crown on a road, but fortunately, my drive is on a hill-side, so it just has a side-slope all the way across. The box blade will be very good at reconditioning the road if there are ever bad ruts or pot-holes. If you lengthen the top link so the blade is riding on the back cutting edge, it will be okay at dressing out minor problems. The rake is going to be the only thing that will pull gravel in from the grass on the side.
It may help to understand the difference in how the box blade is used vs. how the rake is used. The box blade, you are always working "back and forth". It prevents the dirt and gravel from spilling out the side. Dirt and gravel can only spill out the back of a box blade. So you can move material forwards and backwards, but you can't easily move it side-to-side. When working a large area, this is addressed by making passes at the area from multiple directions, but with a driveway that's not an option. With a back blade or landscape rake, you can angle it, and you will "windrow" material that falls out the side to which the blade is angled. Once the material is windrowed in the center of the road, you can then reverse the process to spread it back out again and leave a crown. Crowning is much harder (or maybe impossible) to do with a box blade for that reason. However the box blade's ability to dig in and drag a large amount of material makes it much more suited for big repairs, although I also use mine for daily maintenance, given that it's all I have.
If I had a box blade and a landscape rake, I would think hard about getting a land plane next. I know there are places where a grader blade shines and places where a box blade shines, but there is a lot of overlap between them, and if you have one, there may not be as much incentive to run and get another. That's especially true if you also have a landscape rake, which fills in some of the jobs that a grader blade would do, such as windrowing and crowning the drive.
A land plane is the simplest and easiest way to get an excellent finish on your gravel drive. It has the least learning curve and the least interaction when you're working with it (compared to a box blade where you're constantly changing the top link length). With a drive as long as yours, I would seriously consider getting one. However, you may find that you can do most everything you need to do with the tools you have, in which case spend your money on something else.