If you are faxing and hoping the barcodes will still scan. You will have better luck with 1D barcodes where the potential change in height of the barcode on the resulting fax won't be an issue. http://en.wikipedia.org/wiki/Barcode#Linear_barcodesOpens a new window If you are going to use a 2D barcode like PDF417 you'll want to test sending the fax at different resolutions to see if the built in error correction will be enough to counteract any vertical distortion.
If you are trying to sort a number of standard documents, You would be better off giving each a short alphanumeric code and not the actual title of the document. You will then have a huge pool of available barcodes. A 6 digit code using only numbers would allow you to have 999999 barcodes and that number increases when you add other characters into the mix. http://idautomation.comOpens a new window is a good source for barcode fonts, but there are plenty of other.
By using a reference number instead of long strings of text, code39 or code128 become usable options again.