Lathe Shim

My lathe is ancient. It is a Myford ML2. They started making these in the late 1930s so it has seen some action. I recently bought a set of 12mm lathe tools from ebay. They cost me about £60 and seem to be of reasonable quality:

The problem that I have is that the lathe has an imperial centre height (the distance between the slide and the centre of the chuck). This means I have to place shims under the lathe tools to lift them to centre.

Inevitably I never have quite the correct shim available. Yesterday it occurred to me that a feeler gauge would probably have correct selection of heights. Problem solved: