You could just get yours chromed... though it would probably be cheaper to just get it polished. Since it's aluminum, it'll polish up to a pretty bright shine, rivaling a chromed one.
There are aftermarket companies that make swingarms for the Bandit and you can probably get chrome from at least one of them - polished is certainly available. Here's a few of the most well known ones, there are probably more...
APE RacingJMCMetamachex Their site currently doesn't have a pic of their B12 arm, but you can see one here at
JustBanditsSpondon The Spondon site was acting up for me when I posted this, but again
JustBandits sells these, too.
If you want to use something from another bike, you'll be concerned with all sorts of things. The width where it slips into the frame, pivot bolt diameter, rear shock & linkage mounting, width where the wheel slips in, axle diameter, overall length from pivot bolt to axle, rear brake torque arm mount...