brake booster question

[erikh09]

Hi all,

My 67 GMC 3/4 ton has been converted from power drum/drum to power disc/drum. However, I am not sure the proportioning valve (block) was ever changed. Is there a way to tell? It appears the PO added the adjustable proportioning valve but I am not sure that it ever worked. The brakes never seemed to stop as well as I thought they should especially with new rotors and pads on the front. Also, should the size of the brake lines be changed to 2 different sizes since it now has disc/drum setup? I want to be sure I have this part right since the wife anf kid will be riding with me!! haha
Thanks everyone in advance for your help with this!