@Larry Neal I realize your post is almost a year old, but I thought I would comment. Your AB set is great, and the F2 was not in that scheme for very long so I'd say keep it clean. I don't think there is a way to do a really good job with imitation aluminum color, so I don't worry about it.
I have an AA set which is not what the Southern Railway ran. I am looking for a powered B unit to match mine but they just do not show up for sale.