In said:
I need to be able to post it as a PR release for online access.
unless the image (assumed to be a photo) is already at 300 dpi,
upsampling like this is going to adversely affect the reproduction
quality. In turn, it will adversely affect the image of your compnay/
client.
so. DDT. (Don't Do That)
deal with the image in Photoshop properly from the beginning.
If what you want is an image of the page, this, too, will adversely
reflect on your company/client as one that is not up to speed on the
right way to handle such things.
Use PDF.