I would get a decent box blade. A good heavy unit, one with a swinging tail that can be locked down or free would be best. If you have a welder, add support to the front scar bar and 3pt mount. Hitting lots of rocks is hard on them and the cheap ones will bend like all get out. More weight is better with box blades up until it's too heavy to pull. (then you have an excuse for a larger tractor....:laughing
Use it to get the rocks out by extending the top link some, locking down the swinging tail (if it has one) and extending the scarifiers all the way down. You DON'T want to pull a mound of spoils in the box at this point. That's why you want it tipped back a bit so the loose material can get out and don't lower it all the way, just until the rear blade is touching the ground. It may take several passes in each direction to get the larger rocks out. After you loosen a rock raise the 3pt to bring the rock up where you can roll it off to the side.
After you get all the big rocks out, pull out the scarifiers and shorten the top link to where the box is dead level to 1" nose low. Adjust as needed, but that's a good starting point. Nose down digs more, nose up smooths more. Swinging tail loose digs more, tail locked down smooths more. Then shorten the side link to tilt the box by 2" side to side. (ALWAYS shorten the side link NEVER lengthen it when running a blade to form a crown or change grade. The link is much more fragile extended than shortened. I know. I also know how much the replacement cost is too.

) Run the down side to the shoulder and work edge to center moving the loosened spoils to the center of the road. About 2-3 half width passes in each direction will get you to the center and should result in a 4" crown. It's easier to make the crown with a back blade tilted 30-40degrees , but you can do it with the box too.
If you run a sports car, you may want to decrease the amount of crown, but that will reduce run off and mean a shorter time before you're maintaining the road again. I like a LOT of crown for that reason. Maybe too much for some, but it's what I like.