Yeah Llanafreak. You swap the cold clipping cathode resistor from 39k to 10k, among quite a few other things.
I am currently working on a list of mods for the Windsor, with improvements on the power supply and the preamp. If you are a Windsor owner, list some things you don't like about the amp, and some qualities that you would like the amp to have, and I can make some recommendations as to how to change it.