Cleaning Aluminum Valve Covers

I have a vintage set of Cal Custom valve covers for big block Mopar. I'm trying to clean them up without scratching the base material too much, so rather than attack them with sandpaper or Scotch Brite pads, I've experimented with the drain opener which I use to remove anodizing on aluminum prior to polishing. Although it does brighten them up (and even cleans out the black stuff from the minor pitting they have in spots) it is a VERY time consuming process. The covers are NOT anodized from the factory, just bare aluminum.

Regardless what I've used so far (drain opener, oven cleaner & Greased Lightening...all which contain lye) I will have to stay with the parts constantly moving the cleaning agent around with a chip brush or toothbrush if I use these products because if the cleaner drys on the part it makes streaks and blotches on the covers.

Do any of ya's know of a commercial cleaner or other product that is available in large quantities that I could buy inexpensively, that I could perhaps soak the covers in?

I have a round pretzel container here that will accept 1/2 of a cover at a time, but in order to immerse the cover in it, the solutions I currently have would have to be diluted with water, so much so that I'm afraid they won't work very well....... if at all. I'm also not crazy about doing them 1/2 at a time either.

The drain opener seems to work the best so far, but at $7.00 a quart I'll be in this thing for a bunch of money if I bought enough to fill a container.

If anyone has any ideas that go in a different direction.....I'm all ears.

NOT trying to restore these to any kind of previous condition from a value standpoint, just trying to make them look nice again so I can put them on the Fire-Breathing Dodge Dart.

I tried them on the engine already, and even in crappy condition, they have a REAL nostalgic look to them, and thats what the rest of the car looks like. I can't wait to get these on there permanently. They make the 440 look even bigger than it already looks! LOL Once they're ready to go on, I'll need some old school wing-bolts to hold them down!

Thanks in advance!

George