"DANGER, WILL ROBINSON!"
RUN, do not walk away from anything with "shift kit" in the name. If you leave the "F" out it's a better description. Most of the rear end failures, and an overwhelming majority of premature universal joint failures I've seen were on vehicles that also had a shift kit installed. If you absolutely must have a more positive shift, machine the front and rear clutch pack pistons and pressure plates to accommodate a couple more clutch plates, and leave the shift strategy the way the GM engineers designed it to be!
Jerry
