Well, I now have a restored speedometer thanks to the help I got here. I couldn't budge the needle by twisting and pulling and there wasn't enough shaft to grab with any kind of pliers under the needle hub so I just got a small flat screwdriver and began gently applying pressure under the hub in different locations and it soon loosened and came off.
Once I had the needle off I swapped the good guts from the bad housing into the good housing, pressed the good needle on, cleaned the glass, crimped the chrome bezel and I now have a working speedometer.
I did discover that the good needle was an obvious recent replacement, so now I'm going to try to find a source for a replacement needle and rebuild the old one. In my case a ham fisted PO rendered the speedometer useless through clumsy handling... the instrument appears to be fine, just needs some TLC.
Thanks to everyone for helping.
