If you're going the paint route here's the trick...Spray it with a light color first..Go heavy with this coat to give you the coverage/weather resistance you need to keep it looking fresh...Let that coat flash and then add a darker color as a mist coat..This is the coat you can use as a tint to get that dark,forged color it needs to be...You can actually use more than one color to tint the part if desired to get that "as forged" look...
After the part completely dries use a scotchbrite pad to LIGHTLY scuff and highlight the part to bring out the casting grain,parting line,and other details as needed...
Here's an example using the technique...Eastwoods Zinc phosphate paint was used as the dark tint on this part is adds a nice charcoal tone to the part...