cc1plus is part of the package gcc-c++
Just to make sure you have it installed:
yum install gcc-c++
If it is installed but still no luck then there it is probably failing to replace your custom g++ which may be pointing to a different cc1plus. Try deleting /usr/bin/gcc and /usr/bin/g++ before reinstalling again:
yum reinstall gcc\*
Other than that i am running out of ideas besides an audit. If you are out of luck with the above then let me know and i will try and remember the appropriate incantations to get the list of out of place files.