Answering my own question:

There’ a British railway enthusiast site http://www.internationalsteam.co.uk/cranes/steamcranes02.htm
that seems to have status on many, if not all, surviving steam cranes in North America.

Here’s what it has to say about this MoPac crane.

North Freedom
Mid-Continent Railway Historical Society

Industrial Works C/N 2927 120 tons Wrecker Steam 1914
St. Louis Iron Mountain & Southern #Z-8
Missouri Pacific RR #X-105 1928
M-CRHS 1967
http://www.midcontinent.org/collectn/service/mpx105.html
(Sold for scrap 2nd May 2015)

There was another 18 ton crane also sold for scrap, same day. There is a surviving Soo Line 60 ton crane here.

So I suppose I missed my chance.

RG7