I wouldn't do it. I don't buy "ebay brand" unless I have to. You can get well known brand name aluminum pulleys for about the same cost. Buying the name might cost more, but for 99% of the time it's for a good reason. Check out www.50resto.com for pulleys. Go to mustang parts-> engine-> accessory drive.... ASP makes alum. pulleys for $105, and BBK has alum. ones for $113.
PS- I bought MAC steel pulleys from 50resto for $70 if you want to save a little money.
I agree about avoiding the "ebay special" unless you are certain of the brand. I've had ASP aluminum pulleys on my car for over 8 years and I haven't had one single issue. I highly recommend the ASP aluminum pulleys.