Looks like its just your run of the mill rebuild to me. It should stop the leaks, as far as how much tigher it will be, thats subjective, depends on how bad your existing steering box is. I imagine it will be as tight as an OEM box, perhaps a tiny bit less.
I don't know if your expecting a steering response like modern rack & pinion systems in new cars or if your old box is falling apart. The recirculating ball steering boxes are never going to give you the feedback that a rack&pinion systems does, sure they can be tight, but if you want steering feel like a modern sports sedan, your not going to get it.
You can give the little pre-load screw on your existing box a 1/4 to 1/2 a turn, that could tighten up the steering some. Don't over do it, you'll chew up your steering box if you turn that screw too far.
As well, if your looking for a cheap fix, NAPA and others, sell seal kits to replace the seals on the box to stop the leaks. Thats not a garuantee, since there could be wear on the shafts, etc that will still cause it too leak with brand new seals, but most likely it stop the leaks, or at least reduce the leaks greatly.