Sceleratus,
I think it will look wonderful the way you intend.
I would add though that if you are able to do it I did have a small idea that might be a nice touch.
This is of course merely one mans opinion so feel free to disregard it, but I thought that if you are getting the entire top plate polished that even if you have the raised vent sections, it will blend in to the rest.
If you wanted a small amount of contrast, I was thinking that you could use some aluminum round stock to raise up the vent plates a touch more and either have them polished or anodized in a darker color. (perhaps black?) Then for the vent plates themselves, instead of using something like brass or copper (which tarnishes rather easily) You could keep just try to anneal them so that you get a bit of a multi-hued finish? Or perhaps anodize the top and have the bottom that faces the tubes highly polished.
You could also have the entire sheet bright dipped (think of it like an acid wash that makes it incredibly bright) and then clear anodized to protect the finish and make it very durable. (Lv.3 hard anodize is a great choice for this)
Just a couple ideas my friend. I know that no matter what you choose, it will look fantastic. You have already accomplished so much in this build that anything else is just the cherry on top.
Have a wonderful day.