The problem as I see it, is that the only time anyone sees the hood springs is when they are stretched out, so it just makes sense to paint them that way. You can use a couple pieces of angle iron about a foot long and some threaded rods, drill holes for the rods and holes between the rods for the springs to stretch them out.
I haven't tried this yet, but I'm thinking you may need 4 rods to keep it from twisting.
You might want to order a catalog from AMK Products and compare the cost for exact same new plated hardware, against your time cleaning and painting the original hardware. I have ordered a lot of hardware from them, and it is exactly like the originals. They also have many other under hood items that you will be interested in.