Such + adj. only: Is that acceptable usage? Or should I use "so" only in these cases?

Question

For the word "such", most sources say that it should be followed by a noun (phrase) but mention nothing about "such" + adj.

e.g.

Such confident of him! But can he pull that off?

That's such arrogant of him.

I know these sentence wouldn't be considered problematic if I substitute "such" for "so". But can I use "such" as an adverb in this way to modify only an adjective (but not a noun)?

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M-W's entry of such as an adverb has the following example:

such tall buildings

Of course, that can be read as "Such" + "tall buildings" (noun phrase), but can that be also read as "Such tall" (adjective modified by adverb "such") + "buildings"?

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Related question: If the rule is "such (a) + adj. + noun", why is "such fun" correct?

This question discussed the sentence "It was such fun for all of us to be together". But I think "fun" in that sentence could be considered a noun. So, in that line of thought, that question does not provide much insight to this question I have.

Answer 1

Is the OP perhaps trying to find a loophole or an exception where "such + adjective" is appropriate and grammatical? I don't know of any exceptions, even when the language is informal and vulgar, such does not precede adjectives:

i) That's such bullshitty (Nonstandard)
ii) That's so bullshitty (Standard)
iii) That's such bullshit (Standard)
iv) That's such a bullshit(ty) excuse (Standard)

Person A shows person B an antique photo album. B replies:

iv) They are such beautiful! (Nonstandard)
v) They are such beautiful photos! (Standard)
vi) They are so beautiful photos (Nonstandard)
vii) They are so beautiful. (Standard)

From Cambridge Dictionary,
_{(Apologies for the screenshot because I don't know how to do strikethroughs with the Stack Exchange editor tool)}

Compare

so + adjective	such + noun phrase
you're so kind	he's such a nice person
it was so hot we couldn't work	November was such a cold month

If the OP's own research confirmed that "so + adjective" and "such + noun (or) noun phrase" is considered standard English, then they have to accept it.

Answer 2

Such + adj. only: Is that acceptable usage?

No. It’s wrong. It sounds awful.

Or should I use "so" only in these cases?

Yes, that is a good idea.

most sources say that it should be followed by a noun (phrase)

Those sources are correct.

This question discussed the sentence "It was such fun for all of us to be together". But I think "fun" in that sentence could be considered a noun.

Fun is a noun in that sentence.

So, in that line of thought, that question does not provide much insight to this question I have.

It does provide insight – it agrees with

most sources say that it should be followed by a noun (phrase)

And that quote should be "all reliable sources, in which the following word or words are referenced, say that it should be followed by a noun (phrase).

Answer 3

In a comment John Lawler wrote:

So before adjectives, such before noun phrases, both of them requiring a that clause to define it. So tired that I'm going straight to bed; such a long day that I'm skipping supper.