The green earth ground wire pretty much ties all the components together in the cab so they are all at the same potential. Although Bob's diagram doesn't show it, you could connect the ground wire to one of the mounting screws of the distro block, but it probably isn't necessary.
FWIW, I haven't had a cabinet yet that actually had a distro block. It seems to have been more common to use jumper wires in molex connectors than using distro blocks in older cabs.
You can (should) run a wire right from the earth ground attached to your ac filter to the power supply. I just replaced an old linear power supply with a switcher tonight in one of my cabs, and that is what I did.