He has at least a newer Dana 70 rear, and perhaps a different front.
I agree, don't modify drums.
The difference in 1/4" of brake lining width should not be a significant improvement unless you are pushing your brakes to their limits stopping your truck now. Doesn't sound like it's worth the aggravation to do anything with them to me.
I agree, if you have all the air out of the system and good drums, lines, and properly adjusted shoes you will have a good firm pedal.
Could it be possible that someone has a wheel cylinder installed upside down and the bleeder screw is not on top, therefore trapping air in the cylinder?
If that checks out OK then I would bleed the brakes several times and with different methods trying to be 100% certain the air is out. Try pumping the brakes to bleed, and also try a vacuum bleeder.
Grigg
