The 21.5" iMac power supply is not quite as powerful as the 27" model while it will work you will burnout the power supply prematurely as it will overheat.
It's best not to tempt fate here stay with the lower power chip series (2400S). Here's what I could find: [http://www.amazon.com/s/?ie=UTF8&keywords=i7+2600s&tag=mh0b-20&index=aps&hvadid=860147253&ref=pd_sl_8il3ywk15z_p|Amazon listing here in the states]. I'm sure you can get someone to ship to you.