You shoud be able to restore the original permissions with:
chmod 0700 dirname #basic permissions
chmod a-s dirname #remove setuid bits
To grant execute permissions for all files within a particular directory for everyone in the group owning the files (as well), you would use:
chmod -R 0750 dirname # set all permissions (-R means recursive, or:
chmod -R g+rx dirname # add read and execute permissions specifically for the group
This will also add read permission for the group (execute permission is not worth much if you can't read a file). See man chmod
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