Brake performance question.

[Zurbo]

Recently I've completed a full rebuild of the disc / drum braking system minus the lines which checked out fine.

I've replaced the master cylinder last month since it croaked.
Over the holidays I went ahead and attacked the rest of the system with new calipers, rotors, wheel bearings, semi-metallic pads, new slaves, semi metallic shoes, and turned the drums.
All four brakes are working with a real good stiff pedal but I feel they are not performing wery well.

Since these are power brakes, I would expect to be able to lock them up once I stood hard enough on the pedal. The power assist seems to be working and I can lock 'em up on a gravel road but not on dry pavement.

Maybe I'm too used to my "other" Chevy. They are working somewhat better than before but I guess I was expecting a night and day difference since the old pads and shoes were not semi-metallic and just about shot.

As far as tires, I am only running 255 70 R15's so it's not like i'm trying to stop a monster with 44" swamper tires.

To me it just feels like the brakes just aren't performing good enough. When it's running on the high idle circuit in the cold mornings it actually feels like it's not going to stop at all so I'm constantly throwing it in neutral which is getting old.

So I'd figure I'd ask and see if it is normal to not be able to lock up the wheels on these trucks.

Thanks!