Bob,
You're doing a fairly high style stool. And yes Adam, they had footstools. Winterthur has a few and Chipstone has an amazing oval stool with ball and claw feet with acanthus. For a second or third quarter 18th century upholstered piece, Damasks were quite fashionable. Leather, as Adam suggested, is always a good choice. The turkeywork and wools are probably a bit early for this particular piece (and wools are incredibly hard to find at this point anyway). I'm not sure where you're located but you're welcome to contact me and I can give you the name and number of an extremely good period upholsterer if you need it. There just isn't enough demand for the fabric houses to produce and keep reproduction period fabrics on the market. Shumacher and Scalamandre are two good fabric houses that carry some good fabrics that are close what you need. They both have a decent selection of damasks and chintz as well as some solid cottons and silks.
Hope that helps.
Chuck Bender