Sadly not really doable in SR with the way the tech went.
We can replace arms and legs. Hell, even while bodies for a limited time!
But that is pretty much where the tech curve went - biotechnology and it hasn't really gone much past that.
Heck the modern smartphone JUST came to SR in 2006! (Commlink). Before that, everything was still plug in! (Jack In actually. As you had to install a datajack into a port on the computer for your deck to work!).
But, DON'T despair as there are some really cool things riggers can do, like controlling an army of drones! Or driving a vehicle with superhuman reflexes. And there are some really interesting toys for you to explore and use to ruin your GM's life
And if you really need giant transforming robots. I could direct your attention to the Robotech RPGs by Palladian games. ROBOTECH is all about thanks, planes and other vehicles that transform into humanoid shapes for combat.... Course it's missing other aspects of Shadowrun such as matrix, magic, and body enhancements.... But nothing has everything