|After many weeks of Googling and the accumulation of a significant number of fabric samples (including, memorably, from Pooch Snoozer dog beds), I reckon I've got as close to a match as is possible for the original Firths of Cleveland wide wale corduroy used for the GT upholstery. The picture shows 2 samples (I reckon sample A is the better colour match for the Jensen beige interior colour) against the back of the head rest cushion.
I finally tracked it down at SMS Auto Fabrics in Oregon and it is available in various colours. If you want to buy some, mention my name (Nigel Kieser) as they match samples by owner name as opposed to car type.
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