From some brake"experts" I never even got an answer and others quoted "quite a bit".
So I started thinking about alternatives.
After some searching I found that Landrover series 3 rear wheelcylinders have nearly the same external dimensions and the rest of the Landrover set up looks similar to the Wolseley too. So I ordered a set for some experimenting.
The back plate needs a little modification to fit the studs, but the cylinders themselves are a nearly perfect fit between the shoes. Now I only need to get some new hoses to fit and change the
connectors on the rear brakes. But if this works I can always find new wheelcylinders when I need them.