Ok I found a new pulley for you. Ford pricing was $122.00 when available (discontinued when I ran it through the Ford parts system) but CJponyparts.com has it for only $115.95!?
http://www.cjponyparts.com/PULLEY-PO...-1993/p/PSPP5/
So... I guess you could try and find a LKQ in the junk yard with a pump attached maybe as all 5.0L Mustangs from 1979 to 1993 used the same pulley.
Hope that helps!