Brake upgrade

[LilJohn72]

Hey everyone, I'm not positive that this is the best place to post this or not but I've got a brake predicament. I've got a 72 lwb C10 with front disc brakes, as you would expect, and I use the truck at the drag strip pretty frequently, it is just for fun though it isn't very fast at all, it is my weekend driver, but I've run into the problem of my brakes not holding at the line. When I go to power brake it at the line they seem to slip. Does anyone have any suggestions about what I could do to fix this? Upgrade to an after market kit, replace shoes or rotors? Anything at all? That's for any advice you have!