All these fuse boxes had a clip missing unless a tachometer or other accessory was added. That accessory wiring would include the fuse clip on the end of a wire. Two things I notice in your pics... other than the fuse for dome lamp and lighter well is missing, all those rusty clips need a good cleaning.
The dimmer rheostat in the headlight switch does dim all the lamps on the orange wire(s), inst panel ( the 4 illumination bulbs only, does not effect the 4 indicator lamps ), along with radio lamp, shift indicator lamp, all. So when the rheostat fails all those lamps fail.
Someone once suggested that the abbreviation on the fuse box is INST. and not ILL. because ill translates to sick. Anyway...
If the dome lamp fuse blows as soon as installed, the lighter well may be shorted internally ( I've seen this a few times ). and the ash tray lamp in the 68 dash is remotely located. The light was brought to the tray via a fiber optic strand. I dont recall seeing a fault or short at that bulb/fixture but anything is possible.
Back to the inst' panel. The rally panel has 2 harness connectors. there's a orange wire in both, 2 illumination bulbs on each. So if there's a problem at the pins where the harness connectors attach to circuit boards, you might get lights on only 1 side of your inst panel.
Although basic dome lamp wiring is a yellow wire, 68 model can also have a light at ignition switch and a delay timer in this wiring that further complicates things. And now this has gotten toooo complicated. First clean the fuse box, figure out which fuses blow and which don't. Trouble shoot 1 circuit at a time, the orange, then the yellow.
