Well, I started down this road and wasted a good bit of time trying to get a mirror polish on my panels. I ended up hitting them all with a Scotch-Brite pad on an orbital sander (took all of about two hours) and sending them off to be powder coated. Check with your local powder coater...there are a lot of cool colors available. I used Tigerlac's "Candy Blue."
At the risk of sounding negative, here's a list of reasons why I would not polish the engine bay panels.
<ul type="square">[*] First, a shiny engine will become "lost" in a shiny engine bay. With so little contrast, the effect and hard work involved in getting your engine and panels shiny will be diminished. This is why most hot rods you look at will have lots of shiny stuff on the engine, chrome and polished aluminum, contrasted and set-off by an engine bay that usually matches the exterior color. Personally, I think an clean engine with polished aluminum valve covers, Weber stacks and accessories and pimpy anodized AN fittings will look great against panels that have been powder coated or painted a darker color.
[*] Polishing is extremely labor intensive. If you pay someone to do it for you it will be expensive.
[*] If you don't powder coat or otherwise treat a polished surface, you will have to revisit it every few months with Mother's aluminum polish, or equivalent, to keep the shine looking good. Very labor intensive in the long run.
[*] If you
do powder coat or treat a polished aluminum surface, you will lose much of the luster in the process. Do a web search on POR 15's ColorChrome and Glisten PC products. They seem to work well, but they are tricky and labor-intensive to apply and no matter how carefuk you are the aluminum prep will lose some of the luster from a freshly polished surface.
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Again, I don't want to sound negative but I feel like I wasted a lot of time and effort trying to do something similar to what you're contemplating.
Good luck, whatever you chose to do.
