You pull the cover off at side next to door to reveal 2 cross head bolts and pull the plastic knobs from the dimmer and trip reset then remove the retaining knurled nuts. pull metal panel away and remove the 2 cross head bolts, The whole panel pulls forward. Thats if you have round clocks. The Sc should have a ribbon speedo, in which case I cant remember off the top of my head but be careful not to damage the speedo cable when removing.
The ballast wire runs through the loom into the engine bay. You have to consider if it is work removing it.
A better option is to remove the fusebox and cut the supply wire off there if you want to isolate the wire or just leave it in place and heat shrink the end, it wont cause any harm. It is simple to solder a new wire on the fuse terminal and run it to the engine bay.
Colin