Just guessing here...
Your buddies stock HO should do about 215 - 230 to the wheels. Adding just a Comp would add 120 HP if you get all it says it does. That is pretty good power but the 400 would be at the crank not to the wheels.
Your 96 would do around 180 to the wheels. A good plate (#10 or #4) and maybe some injector (215s or 370s) to get you the fuel, Governor Spring Kit to match or exceed his RPM range, a little timing advance to help things run better, and some AT work to get the power to the ground.
With our trucks it is harder for an auto to match a manual power for power cost wise. If you had a 5sp in your 96, just a plate would match a comp box for about have to cost. In both cases a little more air (turbo houseing or turbo) should be considered.
jjw
ND