@aearch - I certainly don't want to give you more to do but I just re-wired my entire 914/LS3 - every wire, crimp and connector in the car. I prepared for that by completing hours (and hours) of on-line, motorsport-level wiring training from a company called HP Academy. May I suggest you think about redoing that instrument wiring with proper open barrel crimp connectors and heat shrink? Pics below show an example of an open barrel crimp splice in my harness and that same splice sheathed with sealant-lined heat shrink. Soldered connections create a far greater failure possibility than a crimped connection.
I'm near enough to you that, depending on your needed timeframe, I'd be happy to help you source the needed parts, then come by and show you the basics. I can bring all the super awesome tools and the repair (of what you pictured) could be knocked out in less than 30 minutes. Achieving a high quality result is well within the reach of the average hobbyist. I know this because I didn't know anything about wiring ahead of tackling a "from scratch" wiring of my entire car. And yes, everything works.
.