Hi,

No need machined if you can check free rotation of your camshaft, before.

In exemple, if you have problem with one cap, fit your camshaft without your defective cap, and test the free rotation without and with the new cap.
If problem, you can overdrill the cap (ie 6.4 mm. instead 6.1 mm.) and refit. Cap will be exactly in good position on camshaft. Tighten.

Regards

Claude