This Quest will raise Reputation in two of the main nations (Bastok and San d'Oria) plus Jeuno. It does not affect Windurst reputation.
Contrary to popular rumor, this quest has been shown NOT to lower Tenshodo (Norg) reputation.
The following table was compiled by creating a new character and completing no other quests (including the Adventurer coupon quest.) The test character traveled to Selbina from Bastok multiple times, checking reputation at regular intervals. Note: these values are not known to be the minimums for the associated reputation.
Bastok/San d'Oria/Jeuno reputation from Millioncorn: (from zero reputation)