You can try the "garbage bag" or "grocery bag" trick.Scottie said:
Hold a garbage bag or grocery bag over the end of the shaft.
Push the unibushing through the plastic material,
with the intent of trying to get a wrap of plastic material
to slide between the arrow shaft and the unibushing.
The plastic wrapped around the unibushing should take up
the slop between the unibushing and the arrow shaft.
If a -60 unibushing is a slightly sloppy fit,
then the CB unibushing (0.246 outside diameter) may fit just a little better.