Hi Steve,
I too was searching for the wrong word and have been looking for quite a while. Is the Ambla vinyl the special vinyl on the cushions and face of the seat backs of the BJ8? My seats faces are in quite good condition for being used and 54 years old, however, I did reconstruct the seats by cutting out the seat faces and re-sewed new back vinyl onto the original fronts.
As a side note and to show you that you can always learn: For the last 30 or more years I have had my seat adjusters on the outside close to the sills and never realized they were wrong. Helping a friend, new to Healeys but very familiar with TR3s, I suggested he drive my car to get some feel for the performance of his Healey. At the end of the day, he asked why I had the adjuster on the outside as his BJ8 had the mechanism under the seat. Not realizing his point, I indicated I think it was that way when new. No he said with a smile.
That night I researched the adjuster's location and found I had had it wrong ever since I could remember and no one picked it up...including me. Well, I exchanged the 2 adjusters (took me a day due to the exhaust system) and now all is correct. Unless you know something more?
Ray(64BJ8P1)