One source you might want to check is
Free Dictionaries on Sourceforge. The Spanish-Portuguese dictionary comes in two versions with the older 0.1.1 version having a human readable file while the 0.2.1 version uses the SLoB dictionary interface format (Sorted List of Blobs -- who thinks up these things?). Looking at the 0.1.1 version, it has, maybe, 450 entries. I've attached the 0.1.1 file to this message if anyone wants to try massaging it into a usable form.