This is becoming interesting, and confusing for me.
So, if I have understood correctly:
"A boy such as yourself.... "
"...would happen to two men such as us."
"A great man such as John...."
are OK, and in each case we have a type defined by the phrase which postmodifies the noun.
"A great man such as John..." is not citing John just as a great man, it is defining a sub-type of great man. Not all great men, but a great man who is like John...
Great men, such as you and I, ...
is OK too, you and I being examples of great men.
Now, how about:
Such great men as you and I...
is this equivalent to:
"Great men, such as you and I...
or is it defining a sub-type?
There is a problem with "such great men". In that construction, "such" wants to be an adverb, modifying "great". One can use "such" diresctly before a noun without that confusion.
Of this kind: a single parent, one of many such people in the neighborhood.
Of a kind specified or implied: a boy such as yourself.
Of a degree or quality indicated: Their anxiety was such that they could not sleep.
Of so extreme a degree or quality: never dreamed of such wealth.
To so extreme a degree; so: such beautiful flowers; such a funny character.
Very; especially: She has been in such poor health lately.