I got this fork from a very generous BF member, knowing that the 1" threaded steerer was way too long for my head tube. I plan to use it as a threadless setup. I think I know what I need to do, but I'm hoping to get some affirmation from you guys.

Length: to my understanding, I cannot (or should not) clamp a threadless stem around the threaded section of the steerer. My plan would be to cut the steerer tube at the very bottom of the threads (where the cone nut is in the picture) and use spacers under that for height, as with a normal threadless steerer. Is this correct?

Cone: my top cone is obviously a nut right now (with a spacer or two and a lock nut on top of that). I need a non-threaded cone and a plastic insert to center the steerer tube, right? I assume that the cone needs to match the race, and that it would be best to buy a 1" threadless headset, and at least use the top race and cone out of that. Is that the best option? My other option would be to file the threads off the current cone nut to turn it into a threadless cone, on top of which I would install spacers and my cap. Is that a no-go, or is that an okay way to do this?

Nut and cap: I've looked around and nuts and caps exist for 1" steerers (I guess it'd be a 7/8" star fangled nut). I will need to buy these and the right amount of spacers.

I appreciate any and all comments and suggestions.

IMG_20170901_112846449 by jnjadcock, on Flickr