Your other choices are to convert SDLC to LLC2 and source route bridge the SNA stuff. This is the standard approach. Some FRADs do this internally, negating the need for a bridge or router. LAN-attached PCs running SNA apps can use LLC2 to send data to mainframes who also have LAN cards as do 3745s and 3172s. SRB passes the entire session through the network, but this is not a real problem unless you have a big network.
Network hops over two get to be a timing problem.
Routers that support HPR and can act as a Network Node with dLUR can route SNA traffic. IBM has never addressed this problem head-on.