I'm a big fan of poison golems. They are mindless, which makes them immune to a whole plethora of badness, and you don't have to GoR them.
They also come out of construction, which is the same path that gives you the equipment with which you outfit them.
They absolutely *must* be given bone armor, and probably a life draining weapon as well, because they can't be given regeneration. This tends to limit their MR vs. other crazy-late-game chassis types, but you do what you can.
My favorite chassis for late game SCs? The Niefel Jarl
