replaced speedometer driven gear with recommended 40 tooth and still not accurate...

69_340_GTS said
You could take the cable apart and lube it. I think it uses graphite for lube.

Maybe the speedo itself was just sort of gummed-up from not being used for a long time. Anything is possible with these antique cars!

That's sounds like a good possibility on why it wasn't accurate. Just glad it's working now...