It is not available anywhere. The slightly later webbings are your only option. I have just posted this in the for sales section: might be useful to paste here.

It is your choice as the early material is finished with. This is normally used if you are upgrading to the option of retractors. The early webbing does not roll well in the retractors due to the heavy weave of the material: If you want to retain 3 point lap belts then it will look better than any other material on the market as it is Porsche pattern.

I do not see me producing the early material again as it uses a twisted yarn that is very expensive and is only sold in 1 ton quantities. I have used up the last of the yarn. A new purchase of yarn would commit me to an order of, 14,000 metres of webbing to be made. Obviously this isn't going to happen.