Thanks Rob, I think that's why when I was looking for something to use on the racer, I ended up buying something just for experiment off Ebay which was actually a coilover to suit a "Pit Bike" if you know what they are. It was longer than standard which is what I wanted, had adjustable spring pre load and adjustable rebound on the shocker, all very well made, and only $100 Australian dollars or about 50 pounds sterling. All I need to do then was get some other springs made to get the spring rates I needed. Problem also is trying to find/use something that doesn't look too modern which spoils the look on an old bike. That is why I suggested being able to refit the original spring box's to hide the looks of the coilover. The Thornton unit has a spring diameter of about 63 mm which meant I had to space the original spring box's outward about 8 mm either side, and this set up looks good and works well. The only other idea I had was to use a shroud over the forward end which would hide most of the spring. Just me thinking outside the square if you know what I mean. People seem happy enough to make practical changes to their bikes, but still want it looking standard if possible.