JohnRob:
My only caution would be to verify the cluster will operate with a 1K pot instead of the original 500 Ohm.I would expect the cluster to use the 500 ohm existence as a diagnostic.
Thanks. That's why I've gave those two 470 Ohm resistors from both cluster to gnd so the cluster sees almost correct resistance.
Another problem i non-linearity... 
Uh, my mother told me to learn math in school...
That's how it works:
