I'm inclined to go for the non-solid, "inner collar" type. The solid ones tend (in my experience) to drop off the shaft just when you least expect it (in the dark, in traffic) unless you glue them on.

For the collar type, you can cut a slot across the face of the collar and then set the correct grip tension on the shaft with the original circular collet spring. I've got lots of them here.
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One of the few remaining Mk1 owners... #00015