"Worstest" seems to be a morphological problem. "Most least" could be permissible, if somewhat exotic sounding, I think, if "least" is read with its adjectival meaning―"used in names of very small animals and plants, e.g., least shrew"―so eg. most least shrew. "So smallest" doesn't work with any other superlative ("most reddest") that I can imagine off the top of my head. And "brick ancient barn" is an unusual order but not ungrammatical, though it is interesting. (It sounds more like listing adjectives, ie. I'd read a larger pause after "brick" and stress on "ancient", than the other order. MATERIAL AGE NOUN seems to read awkwardly.)