documentation/behavior unclear of (tor-hidden-service)

[ng0 <contact.ng0@cryptolab.net>]

I have a question regarding the (tor-hidden-service) service.

When I have an previously generated hostname, let's call it
"fooschnickens1234.onion" for the purpose of this message, my approach
on a system like Gentoo was to manually place the hostname and
private-key into the /var/lib/tor/hidden-services/$name-i-gave-in-torrc
folder and change the permissions afterwards.

Now this service is unclear about wether it would overwrite the files I
have when the new system generation is done building (reconfigure).

It would be good to know wether the files can be copied into place in
advance or if one has to wait to replace it afterwards.