@Arnie
It doesn't seem the Amiga version of TiMidity can handle .sf2 files, yet?
Anyway, you can find a set of free patches
here (freepats),
but be warned, they sound exactly (sax) like the one you
have already installed (GUS?) and worse for some other instruments.
Just my humble opinion, but i compared some freely available
patch sets the other day and the GUS set still sounded best.
Either you fix the sax for your installation yourself or you
may be stuck with the squeeky sound...sorry :-/