as stated previously, a engine degreaser and wire brush go a long way.
I personally have used purple power for the past 17 years. It will remove paint if left for long enough though. I wouldnt recommend using it in full concetrated form either; it seems to work far better if you follow the directions.
spray off your area you degreased with water. let it dry.
If the area was previously painted I strip it off with paint stripper from home depot/ lowes. goopy shit that is neutralized with water.
I have a wire wheel I attach to the drill for the larger surfaces. for the corners use a wire brush.
80 grit sand paper it doesnt seem to clog up as easy as say 200+. this is just to get your area down to the metal.
use a fast evaporating solvent, i.e. brake cleaner. then go to a finer grit sand paper.
once that is all done get some vht paint your local auto store should have a few finishes you can select from. I seen today there is a "natural cast" vht has available. I may try that one day. but I like the aluminum finish.
hope it helps.