OK FIRST AND MOST IMPORTANT, "the car wouldn't start with inst' panel removed" You need to know that that big red wire to the ALT gauge is firecracker hot at all times. All the power inside the car goes through this gauge. At this point I'll say you're very lucky there haven't been sparks flying, fusible link blown, etc... Try to remember that damn near any procedure you read in a service manual begins with the same Step 1 statement, "Remove negative battery cable". Anyway... Attach ring terminals of that red and the black together ( 10-24 nut and bolt works ), insulate well, reconnect battery and the car should start ( if its not column shift ).
The simplest solution to the gauge screen appearance is premiumdashdecals.com assuming they have for your model. To elaborate... you could dremel buff the screens to bring them back some but you would need to remove them ( spinning buffer would catch and feck up the needles ). In the end the screens would be glossy which isn't correct,,, and that applies to only 2 of those screens shown. That ALT gauge screen isn't going to come back. Sunlight has taken its toll on that one.
And yes the plugged in box is the instrument voltage limiter. You could replace it with new reproduction ( Oriellys I think ) or any one of several different solid state regulators out there.
