Thanks guys you're very generous with your comments.
I didn't like the look of the steel angle iron on the front of the "arch". I trimmed a half inch off of the bricks with a diamond saw to account for the thickness of the angle iron. I then got 10 copper samples that were 4inch by 4inch of various thicknesses and put two bends in each to fit under the brick up the angle iron and over the front. I then shingled them from the center out. It's a little rustic, but beats looking at rust. Not sure how the perlcrete will behave butted up against the flashing. Always wanted some copper details on my house, guess this will have to do.
I plan on covering the entire thing in bonding cement tinted light brown. I also plan on keeping it covered when not in use. Durability will be the thing to watch for the whole project. I worry mostly about movement in the wooden base and footings, followed by corrosion in the angle iron. However, because the acual oven has no mortar I figure I can always jack up and correct the foundation and can always patch the shell. I would be surprised if the angle iron doesn't last many years but I have no data to support that exept for the limited field testing I did on the 1/8th inch iron in the previous incarnation. All told I probably have about $1000 into it and 40-60 hours. At least I've gotten to bake about 50 pies in it. Can't wait to finish it up entirely and really focus on baking.