The 1926 report PQ is refering to is probably the Piper Laney report. That report is linked to the right on this page. In the link, you can either download the report and then save it, or right click and "save link as" to save a copy. If you think you might want to read it again later, I definitely recommend saving a copy if your download speeds aren't so fast since it's a huge file.

As far as PQ's comments themselves, I'll try to take a look through the document when I get a chance. But I suspect it's a matter of which estimate is used, and how the gold was valued.