I have a M70 stainless classic that will be rebored to 416. It was originally going to be rechambered to 416 rem mag.
But would a 416 Ruger reamer cleanup and completely remove the 375 H&H chamber?
Im thinking of going this route for more performance and im having problems finding 416 rem brass anyways.
Let me know thanks!

No it will not; Ruger is much shorter than the H&H, of which the 416 Rem is just a blown out version.
You can make brass from 375s.

As dpcd said it will not clean up the chamber. How is giving up some capacity in a ruger case going to gain you performance over a 416 Rem?

Equal I'll buy more performance not so much.

Plus your mag is already set up for a H&H length case.

Thanks for the replies. Exactly what I was looking for