May an Aussie shed some light on this model designation, because we have all the above here.
Essentially the 80 series came out as the FJ80, FZJ80 petrols, and HZJ80 & HDJ80 diesel models, all with a solid front axle of course. (Still the best 4WD on earth in my unbiased opinion

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Then in Oz in 1998 Toyota released the FZJ105 and HZJ105, petrol and diesel solid front axle models which many people commonly referred to as a 100 series, albeit incorrectly. They are a 105 series with similar suspension specs as the 80.
Toyota then released the UZJ100, HDJ100 in petrol and diesel with an IFS front end using torsion bars.
I assume the same model releases are available in SA.
Reading and trying to understand the castor issues from this side of the screen has been interesting to say the least. I deal with this everyday and it astounds me the amount of change created by a mere 2" lift. That said a saggy front suspension will create a positive biased reading on castor and this should be considered when interpreting the new figures.
But the still remaining -Ve castor outcome is very odd.
That said, we always offer castor correction with any lift, because our opinion is that delivering correct steering geometry is part of the installers task. There are a lot of reasons why steering axis points sit where they do, and a professional should not disregard this importance ever.
But in my view, given I have limited knowledge of the case and can only go on the info from the OP, it is hard to point the issue at the suspension components used as such. The mentioned 'excessive lift' is one possibility, but this would be very noticeable in relation to the height change. I know we measure very carefully at every step when fitting suspension, a total of four times to ensure we understand the outcome exactly. I'd hope the OPs installer has done that.
The description of 'tracking' and severe wandering certainly suggests poor castor angle, and the first thing to point at is the installer or components. We call this 'Sinshu' . Sinshu installed my......
However before I would start presenting the components/brand to the firing squad, I would suggest a thorough inspection of associated parts and steering components. Unfortunately change in itself can sometimes bring out issues that may have otherwise not given cause for concern in their 'usual' running state.
But the basic geometry design of the 3 link front on a 105 series Landcruiser suggests the differential is rotated too far forward, obviously from lack of castor correction, but 2.5 or even 3.5 degree offset castor bushes may struggle to correct this particular example. Bent knuckles can also cause this, but I am merely guessing now because I'm not there. But worth looking at more than just the installed suspension.
Castor correction should have been fitted though, that is a given. But 5.5+ degree plates will not work, don't go there. The track rod at the back of the diff across the radius arms will foul on the arms at this minimal lift.
Find the real issue and this will solve the problem. Start with a set of offset castor correction bushes.
Just my 2c.
Cheers