I have two banks of rocker tabs from another Wyvern instrument, making 32 tabs in all. This will give me more options for coupling than I can shake even a very large stick at:

These will sit across the top of the swell manual, directly underneath the music stand. I think this is an American style, and I rather like it.

Here is the moulding which sat atop the old keyboards. It’s about 35mm too narrow, unfortunately:

And here is the profile. It is slightly angled, so not a straightforward replacement:

So my next job will be to find a local bespoke woodworker and see if they can make me a replacement that the rocker tabs will fit into. The tab blocks are matrixed, so I also have to design a piece of electronic magic to convert this into discrete outputs. I’m idly speculating about doing it with a Raspberry Pi Zero running a bit of Python, but I might not have enough i/o, The second option is to design a circuit that decodes the matrix using a series of shift registers. The second is probably the cleaner approach, but I like writing Python.

Decisions, decisions.