Export the page to PDF, then Insert menu ▸ Choose…, or drag/drop the PDF onto a blank page in Pages v5.5.3. In the Format panel's Arrange tab, set Text Wrap to None, so you can move the PDF image around, and in the same panel, click Original Size so it is not shrunk.
Pages v5 is not based on Pages '09 v4.3, and about 100+ features/functionality never made it into the new application. Pages '09 v4.3 works on OS X Mavericks, Yosemite, and El Capitan — continue to use that if you have it in /Applications/iWork '09 folder.