I'm pretty sure that Global, World & Autos International are all working from the same materials sources - & they'll send you samples (order online); and those are also the sources for GoWesty, Bus Depot, vsip & the other VW guys (although the VW guys do stock some of the 75-76 914 plaids).
World & AI can do both 914 kits & full service reupholstery, and the 911 CW guys swear by AI for 356, 911/912, etc. too.
Unfortunately, they can get black basketweave - but no friggin' beige/tan or brown anymore, which is strange since they just heat-press the pattern into whatever color.
You might try this Belgian carpet source, as they're supposedly a better quality loop pile than the domestics sold here (& maybe better than the German sold here too), according to some members. They may send a sample too.
http://www.lakewell.com/en/products/porsch...rsche-914-69-76