Hello Daniel,
I've never done this (SDH-over-IP with Cisco) but I'd probably go for the ASR1K (if you already have an ASR9K or a 7600, those could work too):
http://www.cisco.com/c/en/us/products/collateral/interfaces-modules/shared-port-adapters-spa-interface-processors/product_data_sheet0900aecd805bad23.html
http://www.cisco.com/c/en/us/td/docs/interfaces_modules/shared_port_adapters/configuration/ASR1000/ASRspasw/asrcfgceop.html