dublenaught,
I have enclosed a link to a bunch of wiring diagrams...pick out the one for your year.
It looks like power comes through the light switch, goes to the dimmer switch and then on to the headlights. All those switches must be good or the little amperes fall out on the floor.
The lights must be grounded. Isn't there a terminal strip on each inside fenderwell where the headlight/parking light wires are made up with the main harness. A quick check with a volt tester would tell you if your power made it that far.
Is there some type of onboard protection on the light switch for the headlights?
A voltage tester of some sort is a 'must have' to follow the power path and figure out what's what!
Stuart
http://chevy.tocmp.com/chevywiring/index.htm