The Jaguar XK engines also used bucket shims – I spent many hours setting them up. If the ones shown are 33mm dia, they are not Jaguar, as they were around 18mm dia if I remember correctly – still got some somewhere out in the garage.
I still have the 0 – 1″ micrometer I bought to measure the shims on the Jaguar Mk10 I had when I was young and foolish. The etched numbers wore off them whichever way up they were, as I remember. They were pretty small as they fitted in a recess in the valve spring cap – I’d have guessed at 15mm diameter, but it’s a very long time since I’ve seen one (I’m not unhappy to say), so I may well be wrong.