The font sizes are nowhere in the plain text portion you are editing, and in any case editing it will damage the file. Please see the PDF specification http://www.adobe.com/devnet/pdf/pdf_reference.html, there is no way in the world you could do this by guesswork (and without writing a lot of software, or using someone else's).
OK, thanks for that. The specification looks mighty hefty, and becoming familiar with it is beyond the realm of possibility for me at present.
I've taken to empirically convering back and forth between tools and one that almost solves the problem is to save from Acrobat as PS, converting True Type to Type 1. Then, pstoedit creates an EMF with the proper text. The only problem is that ungrouping the elements in Powerpoint requires conversion to Microsoft Office Drawing, which causes the letters to be formed by vector graphic blocks.
I think I will give up soon and simply resize all text manually in Acrobat. I have to do this each time the diagram is updated.
Test Screen Name,
Sorry for unmarking your response as the answer. I wanted to draw users to a solution. What I found to work was to use Inkscape to resize the fonts in the PDF file.
I normally wouldn't perform the sacrilege of posting about a product in the same usage space as the products of the forum's host vendor, but this is a vexing problem and it probably wouldn't make sense to purchase a heavy duty product just to resize fonts. I also had 2 people try Illustrator, and both ran into problems (all the text were displayed as some kind of symbol font after resizing), so that's not a solution either. Also, I don't expect any user to abandon an Adobe product simply because they used Inkscape to resize text. I suspect that they are not in the same league. Finally, in my case, while I might be able to get Illustrator at least half a year later, that does not help now. We are expected to be agile, but the processes for getting tools does not support this requirement. Actually, our shop is pretty locked down, so I'm not even sure I will be able to bring in the solution of using Inkscape. But here is the information, for those that can use it.