Device faxg4 oder resolution 1728 does not work?

[webbiller]

Hi folks!
I'm trying to get a Fax compatible TIF . The resolution shold be 1728px 
horizontal. I tried ghostscript 8.14 and the new 8.51 for windows. The 
Device faxg4 is not supported, and the device tifg4 uses a much too hig 
resolution. i coldn't manage to get the desired image size. The 
commandlineoption -g doesnt do anything, -r works, but is not very handy 
for my use.

any ideas?