Plasti-cote has a really nice cast grey that looks close, but like any rattle can paint job, it doesn't last as long. I do recommend powder coating. Eastwoods powder coating system and they have the colors needed to make the parts look correct. Their cast grey looks really nice and lasts forever.
I powder coated almost every part on my car. If it fit in a full size oven it got powder coated. I did my smaller items like my master cylinder, spindles and steering arms in cast grey, my pulleys and brackets in underhood black and my valve covers and intake with their Chevy orange. I even did my rally wheels with they argent silver. They all still look great, and these were done over 7 years ago. They even have a correct coating for the exhaust manifolds.
If you don't have a full size oven at your disposal (DON"T USE THE ONE IN YOUR KITCHEN...it will ruin it and your wife will kill you), you can use a toaster oven for a bunch of the smaller parts. I have a full sized oven in my garage and I have done larger items like my wheels and exhaust manifolds, with excellent results. If you are considering redoing a bunch of parts, then I strongly recommend getting Eastwoods system. They sell the gun for about $70 or they have a kit that includes everything you need along with a sampling of colors that you get to pick. I don't work for them at all, but it worked so well and I was so happy with the results, I do recommend this system to anyone wanting to redo all of the small items in the correct colors and want a lasting finish. If you have any questions, about how it works or more details on my experiences, then feel free to email me...I will be happy to answer your questions.