Preheat a grill to medium. In a small saucepan, bring the chicken broth and 1 1/2 teaspoons olive oil to a boil. Stir in the couscous, cover and let stand off the heat for at least 5 minutes.
In a small bowl, combine 1 tablespoon olive oil, the lemon juice, chili powder and 1/2 teaspoon each salt and pepper. Brush on the pork and let stand.
In a large bowl, combine the mango, zucchini and scallions; drizzle with the remaining 2 1/2 tablespoons olive oil and toss. Season with salt and pepper. Arrange the mango, zucchini, scallions and pork chops on an oiled cooking grate, cover and grill, turning everything but the scallions once, until the scallions are charred, about 5 minutes, and the pork chops are cooked through, about 10 minutes. Transfer the mango, zucchini and scallions to a cutting board; transfer the pork chops to a plate and tent loosely with foil.
Finely chop the mango and scallions; stir into the couscous and season with salt and pepper. Slice the zucchini crosswise into 1-inch pieces. Serve the pork chops with the couscous and zucchini slices.