usually the upper part and the nacelle behind the head light are polished stainless more durable, if you just use the lowers you will have a mis match in color.
Other option is take out front wheel , remove fender and brake and set about the lowers with a polishing mop to remove the grey paint about 4hrs per leg for a reasonable job or a good 6 hrs per leg for a nice job.
I used 2000grit wet paper with solvol (abrasive paste) to remove the laquer and paint then set about it with solvol on a medium mop, then a nice soft finishing mop with finishing wax (supplied in kit) then vienna lime to remove the residue and grease then a good polish with Belgom Alu for natural finish just polished metals.
all up about £35 and you use your normal drill to spin the mops

will post a few pics later so you can see the difference's