I decided to go for the Teleflex SL3 as I fancied a plain black one which was available in the UK. I also fitted new TFXtreme cables which were a bit more expensive but very smooth.

Hope this picture is visible its my first try.
This would have been an easy fit with only a small amount of the side panel hole to cut out. Please don't make the same mistake as I did. When it says the maximum thickness of the panel it will fit is 20mm that's what it means, not 21 or even 20.5. As the bolts were long enough to fit the metal side plate I completed the job with both the new cables and got right to the end when I came to fit the outer cover and the handle itself. When I tightened the centre bolt of the handle that's when you find out that 20mm really means 20mm. I didn't take into account that the wood had swelled slightly over the years and also the leather covering increased the thickness.
I had to take the complete side panel off and remove the new controller to take a couple of mm off the inside of the side panel to reduce the thickness. Took for ages but I'm happy with the end result.

Apologies if the pictures don't appear.