Drawing all characters using GD

I have enough fonts installed on my machine to draw most of the  
world's UTF-8 characters. But they aren't all in one font file. How  
can I use the resources I have to reliably draw any character using  
imagetttext()?

For example: Most of the text I want to draw is regular ASCII, many  
words contain Extended ASCII. Then some of it is Korean, Chinese,  
Japanese or Arabic. I don't know when I'll come across what charset.  
I want to draw them all. Is this even possible?

If I had a list of font files, could I test each to work with a given  
string, until I find one which works?
~Seth