[78-L] 16" Transcription Discs Question

[Stephanie Gaynor]

I have asked on experienced person about this but thought I would get additional input.

What size stylus should I use for a series of 1941 RCA Science Education Records?  Any one familiar with this series of records?  Here is more info:

RCA MS 068219

The Weather, Part 1, 1941, Produced for the Committee on Scientific Aids to Learning of the National Research Council by Jerome Rulon, Narration by Philip Rulon, Copyright by the National Research Council

The label says "use RCA Victor 100% Shadowgraphed half volume Steel needles with 3 ounce pressure on the needle point."  "Record Speed 331/3 RPM"  "Start needle at the outside"

The label is gold on black with small RCA and nipper in dual circles at the top.  Here is a link to some images of the label and disc: 

http://www.stephsrecordsale.com/radiotrans/science-records.html

Here is a link to the Library of Congress Entry for this disc:  

http://lccn.loc.gov/2001659734

They are a friend's family treasure so I am especially timid about experimenting for fear that I might cause some groove damage. I don't have any experience with 16" discs so far, but I am about to pick up a proper table on which to play them. (Technics SP-15 w/Audio Technica ATP-16T tonearm)

Any advice will be appreciated!  Thanks, Stephanie