These chassis/cage components are just nickel steel, right? Unless there's some crazy other components, one option might be to make an electrolysis tank—I do it with car parts like driveshafts, steering knuckles, and the like—it works wonders! Just
don't do it if there's
ANY COPPER or STAINLESS aspects of the parts—I know the whole isn't, but even if there's a small amount—doing that will release some nasty, carcinogenic **** you don't want to make.
The basics are best explained in this video:
Also, this process could be modified to re-plate the target part with zinc, but that isn't covered in this video, specifically.
Personally, what I'd do is remove the rust via electrolysis, give it a good clean with pure acetone or paint prep, and use a self-etching primer base, and then a Rustoleum chrome finish.