With a oxy-acetylene torch, you should be able to heat the shifter and bend it back into shape. Don't do it on the bike. Put it into a vise.
What Metzlers do you have? Or, did you have? 880's? I don't even know what's current for them anymore. The bike should have soft tires, and that's just part of owning a muscle bike. Hard tires, turning a corner or reaching oily, sandy, broken, or wet pavement, and grabbing a new gear and trying to accelerate hard (some or all of these) will result too-often in your circumstances.
One of our long-term members just discovered the left case round 'plate' is an expensive replacement, and may not be available anymore, except used, or new old stock in some dealer's inventory. Fortunately there are bike 'breakers' now advertising on the site.