I was actually writing up a more detailed post where I broke down the size of the Goliath and its crew, and decided not to post it as I was in danger of getting carried away:
The Goliath might have been the biggest question for me, but here's what Wikipedia says about the specifications:
Length 1.5 m (4.9 ft)
Width 0.85 m (2.8 ft)
Height 0.56 m (1.8 ft)
Crew One remote operator
Considering the complexities of casting in plastic vs. white metal or resin, I suspect four pieces for the Goliath itself would work - top, bottom, two sides each sculpted as one-piece sections of tracks/wheels/suspension/sides. Those four pieces would each take up as much room, I believe, as four torso-plus-legs bits, which is to say, not much room at all, considering that's the equivalent of toros+legs, and no multiple heads or arms. The one-man operator doesn't really require much of anything fancy, either - I imagine any of the regular figures from the original Panzer Lehr set could stand in.
The gist of the message I didn't post was that the real problem with the Goliath is that only a few thousand were deployed, compared to a large number of some other heavier weapons, some of which haven't been mentioned so far in the discussion:
At a glance, a few thousand Goliaths were built, compared to...
- 20,000 PAK-36 anti-tank guns (2-5 crew)
- 60,000 Flammenwerfer-41 flamethrowers
- 75,000 Granatwerfer-36 mortars*
- a couple hundred thousand Panzerschrecks*
- about 1.5 million Schiessbecher rifle grenades
- 6.7 million Panzerfausts (only two per sprue were included in the original Panzer Lehr set)
* I believe these were deployed in 7- to 10-man squads: one to two officers, three gunners, and three-to-five riflemen to carry ammo and provide supporting cover; I'm assuming much the same thing was probably true of many of these sorts of special small arms, such as heavy machine guns, mortars, rocket launchers, and the like.
As much as I like the Goliath for its possible uses in a sci-fi context, there were more commonly-encountered weapons that might make more sense having at least three copies per Goliath, or a box that includes three copies of more common weapons but excludes the Goliath in favor of a more common heavy weapon, like the iconic PAK-36 anti-tank gun.
That said, I have a feeling PAK-36 models are much easier to come by than Goliath models, and the larger crew might take even more room than the Goliath would....
It's not as easy a decision as it seems at first glance, especially since, as a sci-fi/fantasty/horror gamer, I'm not the target demographic for this sort of historical kit. If it were up to me and I could ignore the historical gamers, I'd go for a boxed set that includes two sprues, each containing only the parts for a Goliath and a motorcycle with sidecar and crew, plus as many small accessories as could be fit in the remaining space (sidecar-mounted machine gun, ammo cans, field telephones, whatever.)
If I were a historical gamer, though, and looking at it strictly objectively, I think I'd include one PAK-36, a couple Flammenwerfer, three each of Panzerschreck, Granatwerfer, and Schiessbecher, and maybe some extra Panzerfaust, plus a 5-man crouching PAK-36 crew, and a 7-14 standing soldiers to act as crew and officers for the other weapons, miscellaneous ammo box bits, and, as space allows, a couple extra bodies for officers with appropriate costumes and hats and miscellaneous command/communication bits (radios, binoculars, first aid kits, that sort of thing.)
In the name of saving space wherever necessary, perhaps a limited selection of heads compared to the original Panzer Lehr set, as anyone buying theis sort of expansion will probably have a bunch of spare German heads from the original set! The standing soldier bodies are probably redundant: these could be sourced from the original Panzer Lehr set easily enough, so these can be easily sacrificed from an expansion if space is needed.
I couldn't tell if the MG-42 on tripods was ever really deployed in enough numbers to justify its inclusion, especially since (like the Panzerfaust) a couple of MG-42s without tripods were included in the original Panzer Lehr set. (But man, just looking at those photos of MG-42s being fired off those poor guys' shoulders make my ears ring! There seem to be enough photos of that, though, that it has to have been a thing!)