Recknagel make s series of bolt shrouds with a Model 70 type side swing safety. One of their bolt shrouds is based around the original shape. There is a minimum of gunsmithing required and this is only to the end of the firing pin, and the new shroud can be removed anytime and the original refitted.

Recknagel part number 30100-0000 or 30100-3000

They are very well made.

There are also a number of US companies that make bolt shrouds with side swing safeties for Mauser rifles.

These are available in the US from NECG

Matt.