Save to disk - how to avoid underscore _?

Whenever Calibre saves ebooks to disk which contain : or , or ? in the title, these (and other) characters will be replaced by an underscore _.

There must be an option to set a substitute but where?

I'd like to replace : with -
e.g. "you and me: a memoir" = "you and me - a memoir"
and , or ; with _
e.g. "you, he, me" = "you he me"

At the moment I can only do it with search/replace in edit metadata or outside Calibre with an additional software.

I can't find anything in tweaks and am not experienced enough to do it with plugboards or a regular expression in preferences-save to disk.

I have to use 1.47 and no, I can not upgrade.
However the principle of how to do it will most likely be the same regardless which version you use.