I am pretty sure I upgraded to iOS7 before I upgraded Numbers. Not exactly your situation. It worked OK but I do remember there being issues with the way Numbers worked with iOS7 and waiting for fixes. I don't know if Pages had issues in that situation.
Upgrading on the Mac you will still have Pages 4.3 in an iWork'09 folder. Pages 5 will export to the '09 format.
Srry I can't be more help.
IOS Pages v2.1 on IOS 7, and Pages v5.1 on OS X 10.9.2 use new data formats that are incompatible with prior Pages versions on either platform. If you open a previous version document with one of these new releases, it will be converted into the new data format, and no longer can be opened by the prior Pages versions. The filename extension with the new Pages versions remains .pages just to confuse things more.
Pages v5.1 on OS X 10.9.2 has about 100 features less than its Pages ’09 predecessor. This introduces unpredictable content changes to documents created by and expecting Pages ’09 features, when opened in Pages v5.1. The reverse is true on exporting to the Pages ’09 format.
Apple has introduced a genuine quandary for veteran Pages users who now must safe-guard documents from the above new versions. A complete backup of any iCloud and local Pages content is a must before introducing the new Pages applications on either platform, if at all.
Speaking from personal experience- I deeply regret upgrading to iOS7.
Pages has become so laggy and problematic that I no longer can use it with confidence.
Several files will no longer open at all- they are blacked out and for what ever reason will not open despite many workarounds I have read.
In the end I had to retype the files from a print out I had of the file. Not exactly user friendly solution or realistic fix for a program created problem.