Here's a funny thing that I didn't necessarily expect would work, but in fact seems to work. Consider the following postscript file:
/Austin findfont
32 scalefont
setfont
100 200 moveto
(Hello, World) show

where Austin is a truetype (notice: TOTALLY NOT POSTSCRIPT) font. Run gv on this, and it's like, wtf, I've never heard of this Austin nonsense, fuck it, I'll display it in courier just to spite you.

However! Run
ps2pdf -sFONTPATH="/path/to/ttfs" /tmp/a.ps
where /path/to/ttfs is a directory containing Austin.ttf, and /tmp/a.ps is the above snippet of postscript, and you get out a pdf file with Austin text.

It's one of those rare circumstances where fiddly file format conversion tools actually behave better than I thought I could reasonably hope them to.