"except within" is correct and usable in written English.
It is usually used to mean with the exclusion of something within a certain area, time, or group. For example: "The museum is free to enter, except within special exhibitions."
Individual statistics were not kept, except within players' heads.
Little happens on the page, either, except within the busy heads of Chekhov's characters.
Israel defines the freeze as a pledge to refrain from constructing housing except within the boundaries of existing settlements.
None of the items in the exhibition were seen during Steward's lifetime except within the confines of his home.
The bris allowed me to re-experience all these elements, except within a structure that is bound by tradition.
Many of the barriers are placed on hard concrete, so plant roots have nowhere to go except within the planters, which are two feet deep.
He added: "In the U.K. there are very few opportunities for me to experiment except within this little universe I've created.
And so Tuesday did not seem especially memorable except within the somber granite walls of St. Peter's Roman Catholic Church on Barclay Street, two blocks from ground zero.
According to McEnery, "nobody cared really, except within the church where people are much more worked up than in society at large".
And, he argues, it produces college graduates who have no idea how their lives make sense except within this narrow track of achievement".
Within Protestant Christianity there is no comparable central authority, but most Protestant theologians, except within the extreme fundamentalist constituencies, have also moved away from the exclusivist position.
