Very interesting system, I bet you don’t have to ever worry about Mephisto running out of steam with Westminster’s. When I approached my dealer, he recommended Antileon EVO for my Canterbury’s. In his experience, Antileon would be a better match for Tannoy’s due to its slightly ‘warmer’ presentation compare to Mephisto.
My system pics are here,
https://systems.audiogon.com/systems/9445