If you're looking to drop it into an Esky, I know of one in Essendon that's being converted into a MkI. I'd probably go for a worked Zetec, given how cheap a Zetec engine would be in comparison - they only imported about 200 ST170's into the country ever.
Zetec with quad throttles would go nicely. I've seen it done.. and heard it!
http://www.youtube.com/watch?v=4waFX8TIYEs
If not for an Escort, then I don't fancy your chances of finding one. They occasionally pop up in crashed cars... just keep an eye on Fowles and on eBay.