Chicken, no way. If you have have used the lathe, turned a pen as good and as close as that then the answer is a big fat NO.
You will find that the standard bushings on a Rotur Mandrel are just shy of 9.5mm. Some of the slimline pen kits are smaller. can be as much as 0.5mm.
Just to try and make things a little easier and closer I measure any new kits i have and measure the bushings as well with a digital caliper. (used to use none digital but the eyes are failing
)
As I have so many slimline bushings (old and new) that I have to measure them or face getting them wrong. Yes they do wear down a little if you are not a chicken.. 