Along, something doesn't sound right here. As for the shim stock, this is the only way I've ever used it. It comes on a roll, and you cut and trim to fit your needs. Don't worry about hardness of the stock. I don't know of any "pre - made" shims for this application, maybe others do.
As to the gauges, you're adding shims to make the chamber area longer. If the No-Go gauge goes in, it's too long already. The go gauge should just fit with light "thumb" pressure on the back of the bolt, allowing the bolt to close into the camming piece and barrel. If the No-Go fits into that "bolt locked" position, the chamber is too long for proper head spacing. The other builders need to add their expertise here, as it seems to me Along is moving in the wrong direction with this problem. Also, if you haven'd done this yet, the bolt is normally stripped of ejector and extractor components, so you are sure you're only working with the bolt face to chamber fit. The extractor/ejector will cause the gauges to not "seat" on the bolt face properly, incorrectly indicating a shallower chamber length than is actually present.
But as I said, the more knowledgeable builders need to step up and add their experiences here. Sounds to me like Along could use a friend here who has been thru this before.