300,000pg PDF won't save after combining is finished

Hello-

I'm attempting to create a 1.6GB PDF that continually errors when saving. The error states that i've run out of memory but i'm using a machine with 8GB of RAM and 30-70GB of virtual memory (another post said this may help). We have successfully created other files nearing 1.4GB at 250K pages with success.

Any ideas?