The problem with making engine mods is that now the engine behaves differently. In the case of a modified 090 it appears that the engine idles at a different RPM than a stock unit and I have a wonderful stock 090. When I build race engines I am accustomed to do whatever is needed to make it work. When I go cut trees or logs I often encounter enough surprises so do not want any extra surprises. So since you have found good sources for clutch springs go for it. Take any spring you have and grind the end off of it. Then take a quality propane torch and heat up a coil as hot as possible and stick a screwdriver into the last loop prying it out to make a connecting link. You may have to repeat the heating process up many times as it will cool off pretty quick. Once you are satisfied with the shape of the connecting coil heat it up as hot as possible then stick it into a container with ice water. Repeat the last process several times only heating it less and less each time. Now you have it tempered go cut something. However if you have a cutting torch or a better heat source then use that. Thanks