There is a lot about this on this Forum (a lot by me)
I have a coil over from USA the forks have been on a twin and raced and now on my Comet
it has some trick plates so I can keep the coil spring anchor in case any rivet counter who doesn't ride wants to but back the original spring
better than Girdraulics until the fork tubes rust through (around 2090)
I will have to change when I go for disc brakes