If I were a rich man...
can be written as
Were I a rich man...
Is this rewriting also valid after 'as'?
He behaved as if he were a rich man...
He behaved as were he a rich man...
If I were a rich man...
can be written as
Were I a rich man...
Is this rewriting also valid after 'as'?
He behaved as if he were a rich man...
He behaved as were he a rich man...
Your two sentences have completely different feelings about them tough they have the same meaning
If I were a rich man...
Were I a rich man...
using "if" emphasizes the hypothetical-ness of asking the question, whereas the second may convey more pondering
He behaved as if he were a rich man...
is correct
He behaved as were he a rich man...
is incorrect, but could be corrected to
He behaved as though he was a rich man...
As a side note: "Were I a rich man" would not fit into the song as well as