instrument cluster ground

Now, that's by golly GROUNDED!!! I'm not finding fault, 'cause I believe overkill beats the hell out of no kill.
That said, I would bet dollars to donuts that a single wire from any of those points you daisy chained to a good solid chassis ground would work just as well.
The stock arrangement used the contact between the metal dash frame and the metal cluster assembly via the cluster mounting screws to ground the cluster.
Over the years, rust, corrosion, vibration and gremlins have made that system "iffy".
And if you're gonna work on the cluster in the car you'll get nowhere without a separate ground wire.

ATB

BC