I built a 7' push blade for my L3200. I use it in conjunction with a rear blade, on a 600' curving driveway. The rear blade does most of the work; the push blade clears a parking area by the barn and garage. When the snow berm made by the rear blade gets too big, the push blade will get it out of the way in a sawtooth pattern.
The push blade only works on a straight line push. Since the forces on the blade tend to lift the front wheels, you have very little steering until you lift the blade. Then, you have a big chunk of your traction on the front axle; you'll need something on the 3ph to keep rear wheel traction. At 500 + pounds, the blade is a load all by itself.
You know your driveway length and shape. This blade will darn sure push snow. It is generally used in parking lots, where it pushes the snow into big mountains. It likes flat surfaces; if your driveway has a crown, make sure the skids will allow the blade to clear it with an inch or two - I use gauge wheels to keep my blade up about 2'.
Any opinions on their ability to clear snow from gravel driveways? Thanks for your thoughts.