I think Cisco has reduced the minium bandwidth requirement to ~ 900Kbps per 10,000 BHCA for the Intracluster protocols (900k min). Additional bandwidth is required for the SQL replication. The sugested total minimum bandwidth is ~ 1.544 Mbps.
Your greatest concern is going to be the maxiumum round trip time specified of 40ms (or 20ms one way). This may be a problem given the distance you are trying to run this over.
Cisco have a good internal application note describing the requirements and caveats that is worth a read.
Hope this helps
Steve