Here's a before photo.
I used this liquid cleaner which contains Hydrofluoric Acid and sulfuric acid. Following the instructions I mixed 1 part cleaner to 7 parts cold water and let the parts sit for awhile and not to let the cleaner completely dry. I was super careful and wore gloves and eye protection.
The next steps were to use a pressure washer and clean the parts. I gave the parts a quick wash with the hose before using the pressure washer. This is a good idea as I ended up covered in water rather than the chemical cleaner.
This is the final result. Not 100% but depending how picky you are it does the job rather good. I might still end up painting the parts in an OEM cast aluminium spray paint but all around I think it does a good job. If i did it again im pretty sure id get a better result with better placement of cleaner in certain areas and leaving it sit longer. Anyway just thought id share