Saving as a pdf from flex 8

When your "Print" screen comes up try checking the "Print Border to Paper" button.

 

pdfs from flexi require the document size to be the same as the image size, otherwise it defaults to the document size and the file is left to be some portion of that page size

 

What Jcuminale states is true... File > Export PDF does retain the document dimensions. If you need to keep the exact dimensions of your job, adjust your document size in DesignCentral (default when nothing is selected on screen). Align your 8in. job to the middle of the page, then go to File > Export. Select PDF and uncheck the "Suppress Options" checkbox. Another dialog box will appear. Verify "Scale to:" is set to "Full Size" and "Include border" is checked. Your PDF will be saved exactly as you see within Flexi.

Adobe has a limit to how big you can save a PDF file... I believe it to be around 110in. long, but, based on your post.... you are safe here

 

Not sure if this applies to Flexi 8 (I am still using 7.6) but when I need to do a PDF I have a template with a border and some company info. When I select the Apply Template button and select the template I created everything within the file is shown within the template scaled as large as possible while still fitting within a predefined drawing area. You can also ungroup the items and then move/scale as desired within the drawing area.

HTH