You can grab it here:
Size: 5.5 mb (a little smaller than version 1a )
http://www.jkasiege.com/esm/maps/siege_jhoth1b.pk3
This is a remapped Cargo with enhanced visuals (IMO). It has more room and minor things like the addition of a ninja route, fixed the wonky doors from Cargo, etc. This version removes all of the little detail from the vents which some people claimed got in the way (even though they were clipped off) but I removed them anyways. Also a new wook trick works on Obj 2. Oh, and the turrets don't shoot directly into the last D spawn any more.
The general layout and objectives are the same as Cargo. This version uses Cargo classes, and the .zip includes an extra pk3 (zzzjhoth_skins.pk3) which contains the Hoth-themed class models. The turret hacks are tech-only (I think anyone could hack in regular Cargo).
NOTE: Some people didn't like how the jhoth skins/models overwrote the Cargo ones, so if you were one of those people just don't yews the zzzjhoth_skins file.
I can literally think of no reason not to just leave this in your base folder (if you already leave Cargo in base).
Thanks (again) to Oink for letting me do this.