Adding Ethernet segment to Token ring

We have a 200 node token ring network, using IBM 8229 Bridges & MAU’s. We are planning to build a new building in 2 years. The new building will use ethernet.

I would like to create an ethernet segment to add a NAS server and to learn from.

I have looked at a Token Ring Switch (Madge Smart deskswitch) with an ethernet module and at a Blackbox token Ring to Ethernet bridge.

Any preferences?

We do currently have a Cicso 2500 router with a spare ethernet port. The routers primary function is to connect us to the internet and to another network we share data with. We could use this, but are afraid of a performance hit.