I am attempting to find specs. for low acidity paper to be used in conjunction with
photographic prints; i.e., as spacers for storage, and as background
when displaying photgraphic prints.

The best thing I can find is ISO standard 14523 which relates to the
Photographic Acidity Test.

The US Library of Congress, who are pros at archiving important
documents, spec the following for photographic boxes which are used to
store important photos.  The same conditions probably apply to your
case.

With regards to acidity, 

"The paper stock should have a pH of value within a range of 8.0 - 9.5
as determined by TAPPI T 509 om-88, cold extraction (modified by
slurrying sample pulp before measurement)."

From personal experience, acid-free paper is the way to go.  Almost
all photographic shops sell it, many mountings are acid-free, and so
on, so you should have no problem finding these materials.

The quote listed above comes from this site:

http://lcweb.loc.gov/preserv/supply/specs/300-361.html

The root directory is at:

http://lcweb.loc.gov/preserv/supply/specs

where you can find all your heart's content on how to preserve
documents of any type.

Cheers!

I observe that you have posted almost the same question on this website twice.
I would advise you to remove one of them to save money.

Let me know if the following links help you in any way

http://www.georeviews.com/Office/Paper___Other_Media/Photo_Quality_Paper/Plain_Photo_Quality/index.php

http://www.digitalauthor.com/content/foc_cs_artpapers2.shtml

www.hpsupplieslink.com/uploadLinks/5982-1564ENUC.pdf