Alex I don't know how far you got with hunting down this update but I know v2 is 6.1.2.0 and v4 is 6.1.4.4 so I'm almost certain we need v3 :) Now for the tricky bit, finding it! It was only out for 24 days before v4 was pushed so this could be tricky.
Well I know the URL is this:
http://au.download.windowsupdate.com/c/msdownload/update/software/updt/2014/11/windows6.1-kb2977759-v3-x64-express-{40 A-Za-z0-9 characters}.msu
Now to try the 178,689,910,246,017,054,531,432,477,289,437,798,228,285,773,001,601,743,140,683,776 URLs
Apparently that's 178 novemdecillion, aka enormous lol.