Welcome Andy and thanks for the kind words. Can you drop a couple of photos of the chassis? Typically the pinch bolt (if fitted) is removed. I remember the model of chassis, but I don’t have a vision of it in my mind.
Excessive camber wear on all four corners is not too unusual in karts due to the extreme caster angles run, and the dynamic camber change they cause.
Otherwise, I wouldn’t say there is anything specific to older chassis perse. The soft/stiff thing to me is very relative and I’m still not convinced that chassis actually go soft. Rail and spindle C bracket sag are real, but in terms of going “soft” I think it’s more perception over reality.