1 1/8 is the standard fork size on those frames. I have a CFM1 with a stock rock shox Mag fork that i have managed to switch over to the same fork you got.
My personal opinion FWIW, is those forks are real cool and unique, so worth keeping them on your bike.
If you decide to go for a new fork, there is a member on here from Italy that put an amazing ritchey carbon fork on his CFM1 and it looks real good as well.
These newer forks will probably have to be threadless and you will have to also modify the headset and stem.
Just do a search for CFM1 as a keywork and the thread will come up.
Hey Thanks for your reply.
Yeah the original fork is cool and unique, But mine has started to rust in places... I may have it resprayed.
After all this I have now come to the conclusion that my bike has an un original 1" quill with a shim! The original looks miles better!!
Do you know what the original stem is called?