So far as I know, (other than the loader) you have three implements in the “gravel road/grading” category:
1) Box blade: By adjusting the three point you can slope or crown, create ditches and turnouts, pull gravel from the side of the road back toward the center, fill potholes, cut out and repair wash. The blade itself can cut or smooth depending on how you set the top link on the tractor. If you have hard packed roadbed, new ground with roots, old asphalt, or anything else the blade isn’t cutting adequately, drop the rippers. VERY versatile tool for what you describe. Takes a little practice to get good with it. By a little, I do mean a little. You can achieve good results pretty quickly and you don’t need to sit at the feet of a master to do it.
2) Land plane: a cousin of the box blade. Good at conditioning and maintaining existing gravel/dirt roads. Levels, fills holes, etc. Also has rippers if road is uncooperative. Takes less skill than box blade. Is arguably fastest option for maintaining a dirt road in relatively decent condition as you can travel 5 to 7 mph and get good results pretty much immediately. Not exactly ideal for anything other than maintaining an existing road.
3) Back blade: No rippers. If it doesn’t dig in, it just doesn’t. Works great for windrowing material (moving it side to side). The box blade and land plane both have depth control. A backblade doesn’t. Backblade is very versatile but it also takes the most skill to use.
I have used, and still use, box blade and a back blade. Use the box blade for most things. Backblade used to pull gravel from ditches back to road once a year and the rare snow plowing.
My vote is get a box blade.