I got the whole cluster reassembled enough to test it out. Getting the gauges all pointing the right way was a pain, especially the battery gauge. Lightly press on the needle when it looks like it's pointing the right way, take your finger off, and it's pointed off to one side a bit!
But I eventually got them all on correctly.
On the test drive, everything worked, but the speedometer was messed up. It's response was VERY slow, and probably not accurate.
One thing I found during disassembly - all the gauge pointers are on plastic shafts which press onto metal splined shafts in the actual gauge. Except the speedometer needle. It has a metal tube pressed onto a metal shaft.
Since the speedometer wasn't working right, I took apart the cluster that came out of the car, since I know how to disassemble the speedometer now. I carefully and gently turned the speedometer needle counterclockwise while pulling up on it, after about 4 turns it came off the shaft.
In the other speedometer, I think I bent the shaft by prying the needle off with 2 screwdrivers.
Anyhow, I found the problem. This speedometer had about 6 teeth broken off the little blue gear in the odometer motor. I'll replace that gear with the one from the other cluster and put it back in and see how it goes. I already turned its mileage up to match.
Another disappointment was the color of the needles I painted. The orange paint looked pretty bright, but when the needles were against the black gauge faces, the orange was pretty dark. I don't think I'd have liked it that way.