Sunn didn't specify cabinets for guitar or bass in those days. It was a mix and match, use what you want idea. However, you can be sure that it was not designed as a bass cabinet. OTOH, IIRC, John Entwistle used Sunn 412 cabinets (I'm thinking 412M, but I really don't know) as part of his bass rig, along with 118 cabinets. The Sunn 412 cabinets of the day were 4 ohms in order to get the max power from the Coliseum amps, which were stable down to 2 ohms, as was the Model T.