There is a resin model from Forge World currently available.
It wouldn’t be too much of a step to have a plastic kit of this Land Raider? Essentially the Spartan is a stretched Land Raider.
It would mean producing a new hull for the plastic tracks, but that would mean replacing potentially one sprue with another.
Of course this would mean returning full circle to the original plastic Land Raider model which was released in 1988, well nearly.