Well from what i`ve read a lot of these bikes were actually painted from the factory, i`ll be shot down if i`m wrong but thats what i`ve read.
Use a paint stripper once you have it fully degreased, make it a good one too, but dont leave it on to long in case it effects the ally. You can get an acid based ally cleaner but its useless if the metals been painted.
Once you get the parts clean have a think about whether you want to leave them bare, polished or painted, each has its advantages and drawbacks
Cheers
Troppo