1/2" sounds tight, but it's also going to depend on your suspension setup and tire profile.
Below is a video of a leaf spring suspension movement,
They had low profile tires (I'm guessing 40 series), now imagine if those were 15s with 50 or 60 series how much additional tire flex you need to consider.
You could reduce the suspension movement, using the delrin shackles, a panhard bar, or watts link.
And you could reduce some play between the differential and the leaf springs by removing the rubber mounting pads, and using a thin (1/4" or so) "lowering block" between the perch and the spring for a solid connection (I have mine setup that way).