Kentmere's Kentona (will react to lith developer) was marketed by Tetenal under the name "Art Sepia". If you can get your hands on a packet of this, it'll be OK.

Pulling out of the daveloper is what Bob means, I guess. The idea is that the blacks should not be developed to the desirable point, for they will darken once the print is in the fixer. I can add that some papers change (shift in colour, darken) when drying, especially if they are toned after lith processing. Read the Rudman book, it's great...