Sport 9" rear axles are really only beneficial to Gen 1 4cyl guys for a drop in affair since both have a leaf spring rear, where as Gen 1 V6 trucks all have coil spring rear suspension. The only thing that would be beneficial from a sport on a Gen 1 V6 would be the axle shafts themselves if they are the same length and spline count.
Gen 2 LSs also have a 9" rear with disc brakes, albeit a bit wider than a gen 1 V6 9" rear axle, are better candidate for a Gen 1 V6.