Yes, poly is metallic. Boy, they really slathered the paint on that toolbox.
The 1955 Steelglow Gray Poly is very similar to 1953 Cadet Gray, which is sometimes but not always listed as poly. Vintage Jeep Paint calls their version "Cadet Gray Poly" (see
https://vintagejeeppaint.com/shop/ols/categories/willys-overland-1942-1952?page=4).
Those two look much closer to your paint than the darker 1954 Persian Gray Metallic or Gale Gray Poly, although matching colors in photos is not very reliable. (Your photo looks like it was taken with a mix of daylight and tungsten light.)
Your serial number is relatively late in the 1954 model year -- I'm guessing a couple of months before the changeover to 1955. But I wouldn't have thought that was late enough that they would be starting to switch to new paint.
If you're not having luck with paint dealers, maybe you could try a small can of "Cadet Gray Poly" from Vintage Jeep Paint and see how that looks.
Derek
P.S. It's odd that some of Alan's posts are now visible to me and some are not. Alan, I would be interested to know if you can think of any difference in how you posted your two replies on the morning of October 30 -- one is visible and one is not.