You've got ball-screws, probably really good ones, and high-quality linear slides. Try to remove and reuse them together - the alignment is critical, and you don't want to disrupt it and have to realign everything. Heavyness isn't altogether a bad thing, especially in elements that don't have to be moved. It works in your favor when cutting tough materials like metal.
Cut away anything you don't need, but try to keep the structure intact. You're going to have to mount all this stuff somehow anyway, and aluminum is as light and rigid as anything you'll likely use.
It's hard to tell from the pictures, but is the stage moved by a powered nut? That's how it looks, which might be a complicating factor, especially if you need to change over to a powered screw.
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