Parking brake help?

Have a '48 Buick with a SBC and turbo 350 trans, 10 bolt 7 5/8 '90 Camaro rear with 9.5 in. brakes. My problem : can't seem to get the park brake to hold. I have put all new brakes (shoes, wheel cylinders, hardware and new drums) and new brake cables. I removed the foot pedal assembly and cleaned and lubed it and it seems to work just fine. I tried hooking the front cable from the foot operated park brake directly to the rear cables, couldn't seem to get enough application, only made the rear brakes drag a little. Then I made a lever device to ad to the mechanical advantage and the brakes apply a little more but I have to have the cables so tight that there is some dragging of the brake shoes. Can't imagine what else I might do to make this thing work. Anyone have some ideas? Thanks, Topless.

Is the pedal assembly from the same car as the rear end? Sounds like they are not made to operate with the same travel.

if everything is adj. up tight it dont take a lot of travel, be sure the shoes are adj. up the cable is tight, and it should hold
the car. you do have the hand brake bar or link installed im sure. if everything is adj. up then it sounds likt the link is to short. :HMMM:

Yup, I have full contact with the shoes and the drum. The cables are adjusted properly and with the drum removed I can see the movement of the park brake arm and the shoes move out. I made my own likeage for the cables. The pedal is from the '48 Buick and it seems to have enough travel but that could be it. I have put together quite few Hotrods and I have always used 8" or 9" Ford rears. Never had a problem like this, the park brakes always worked just fine. I feel like I might be overlooking something simple. Thanks for the input. Topless.