I have an LS1 axle, brakes, as well as LS1 cables, body bracket, and handle lever installed in my 91. The handle pulls all the way up but the brakes don't engage 100%. The car can still be easily pushed forward (but not back). I know you can adjust the shoes inside the rear rotors but I have no idea how. Anybody?

 

it should be self adjusting.

the parking drum sits on the wheel cylinder thing that spreads when you pull the e-brake handle. If you look there you will see that one, if not both, of the piston things has a serrated nut behind the head. That "piston" for lack of a better word, will screw out. That will allow you to put spread the brake drum, bringing it closer to the inside of the rotor. Then the brake should work better.