Your tall case Georgian clock sates to circa 1800 and was by Atkinson Ormskirk. These sell for $450 - $500 on today's market in non-working condition. The best way to sell would be through Craigslist or a Facebook sales forum in your area as well as through a local consignment shop or your newspaper. Ebay is great, however I do not recommend using Ebay in this case because shipping/packing this would be rather challenging.
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I used past auction records that are in a sales database; worthpoint.com