The SR-Lambda is the normal bias original model.
I would recommended something vintage, made when overkill was the name of the game with quality connectors, over sized transformers and not every penny pinched. If that isn't an option then a 400w unit would work just fine.
There is also the option to just change the voltage on the 007tA. It might require some soldering and perhaps adding a wire or two to the primary of the transformer but it's easy enough to do.