even bored out to 24mm you perhaps wont get a single bolt clamp bar end around the curve.

so you have to make a bar end that has a hinge or a 2 bolt open face plate ,

so as to open and close without needing to go around that curve.

Note I said Make rather than Buy.

Perhaps figure 8 bend Trekking bars will do the job, if you lack the shop tools to make your own inventions.