Clutch switch has nothing to do with the headlights, just for your start circuit.
Do neither Hi or Lo work? Does it make any difference whether light switch is in Hi or Lo position?
Fuse for Hi is #1, for Lo is #2 - both are 15A.
You do want to check the condition of the interconnect plug from the left bar switch - follow the cable down from the switch to the connector plug - make sure that both ends are clean making good connections; if oxidized you can buy a cleaner/conditioner from Radio Shack called DeOxit; then use dielectric grease afterwards to ensure that it stays waterproof and free from re-oxidizing.
Repeat the process for the right bar switch - NOTE: the right bar switch must ALSO be connected in order to get the lights on - the power loops through that switch assembly.
So ensure that the right switch is also connected and its connector plugs equally clean & in order.
Remember too ignition needs to be on also. Does your ignition power up as expected?
Other troubleshooting: I know you're putting this thing back together
Do any of the lights work? Parking lights - front &/or Rear? Brake light? Turn Signals?
Do you have a Voltmeter?
Reference all your measurements with the black lead on the battery -ve.
Ignition needs to be on.
1) Check for 12V at connector plug pin with the yellow/white wire
If it's Good, then check for 12V at the white wire (switch side of connector) with switch in Lo and 12V on the Yellow with the switch on Hi.
If all of that is good, then problem is either in the fuses or the lamps.
2) If you Don't have 12V on the Yellow/white don't bother checking the high & low outputs described above.
Instead Check for 12V at the yellow/white on the right bar connector plug - will be yellow/white on the harness side connecting to an orange/red on the switch side which should be just a loop connecting around to the black/red on the harness side. Then check that you have 12V on the black/red - that originates from the ignition so hopefully you have that present.