Not today, but on Saturday I swapped the gearbox out for a much shorter one with a plated center diff, swapped the rear diff out for a very tight viscous, and replaced the rear left hub so that the wheel is actually straight and doesn't have permanent positive camber!
Handles completely differently now, the old rear diff was practically open, and the old center was just as useless.
It'll happily be thrown into corners sideways in gravel now, which is exactly what I wanted.
Here's hoping I can handle it at the next hillclimb!
The built engine will go back in next, have sorted all the noises and it'll be ready for another tune when I have the money.