Once you get the stock MC off, next you need to break down the 4 way T connector below the stock MC.A 10mm flare nut wrench will work best on the flare nuts without stripping them.  Be sure you note which line is which before you complete the disassembly.

Next turn your attention to the stock MC.  You will need to use a pair of snap ring pliers to remove the plunger assembly. Be careful, its spring loaded and will go flying!!!

Now some quick modification to the sleeve.  You need to round off the top part from the tiny taper it originally has.  This allows the plunger to fit the GM MC piston.  I used the sanding attachment on my angle grinder to do this, but I small file will work as well.  Don't mar the flat surface of the next ridge as it will also sit against the MC piston. Also don't scratch the surface as that will compromise the vacuum seal and leave you in a world of hurt.

Next you need to adjust the depth of the booster piston so that it sits closer to the firewall.  To do this without removing the entire booster either have an assistant press the brakes all the way down or wedge a 2x4 on the brake pedal to do the same.  This will expose the piston rod.  Using a set of needle nose vise grips clamp on the rod making sure that you are not clamping on the end nut.  Using a 7mm socket tighten the cap nut on the rod a few turns.  This will shorten the length of the piston.  To check for the proper depth, slide the aluminum sleeve over the piston and mount the MC.  Looking from the side, the MC needs to sit flush to the booster housing. I also drilled out the center of the sleeve some so that I did not have to shorten the rod as much.  You want to keep the rod length as long as you can so that you don't have a low pedal when your done.  Once you get the optimal fit, replace the seal and grease up and replace the plunger (there should be plenty of vacuum grease on the seal to smear some on the sleeve).  Bolt up the GM MC!

Now its time to clean up some of the stock lines.  I started with the rear proportioning valve.  Remove the entire assembly including the break line to the rear axle.  Also, you will want to remove 1 of the entire brake lines that run from the old MC.  There is a connector in the middle.  When your done you will have 3 lines and the BP assembly removed. Bend the remaining line to the rear axle line.

Now its time to create you new lines. To get this done you will need adapters to convert the MC ports to 3/8"-24, a few 8" lines, an adjustable proportioning valve, and a few 3/8"-24 f to 10mm-1 m adapters.  Here is the way I did it.  Looked great on the table, but while installing it I managed to cross thread the adapter block rendering it completely useless.  Since no other blocks with 3/8"-24 inputs to 10mm-1 outputs were available I had to reuse the 4-way T block and weld one of the 10mm flare nuts closed to cap one port and a SAE to metric adapter for the line from the MC.

Next, I made a bracket to hold the proportioning valve in place.  It bolts to the fender well.

Now bolt up all the lines, bending them as you need (a good 3/16" line hand bender will go a long way!) to get them in position and have room for adjustment. The bends needed to clear the evaporation cannister are tight, but can be done. Recheck all connection and fill the MC with fluid.  Switching to the appropriate adapter for the Powerbleeder and bleed the system.  If you dont have a powerbleeder you may want to bench bleed the MC to speed up the bleeding process.  Check for leaks.  Pump the brakes to check for a firm high pedal and recheck for leaks.  If it seems OK in the driveway, do some slow controlled stops and recheck everything.  GRADUALLY start increasing the speed and testing your newfound braking power before you call it a wrap.