Geoffrey,
Thanks very much. Looking around more, I'm not inclined to disconnect all that you mentioned, so will probably just leave well enough alone and reassemble once I get the clock back and reinstalled. Also, it occurred to me that the bulb I actually replaced was probably for the low fuel light, not the fuel gauge itself. Will probably just swap that back and call it a day.
As you mentioned, the wiring is from the restoration in the 80's, and I am very concerned about causing more problems, so will reassemble *gently*. :-)
Thanks again.
(p.s. - batteries disconnected!)