The GEC u52 has nothing on 422.
Hands down.
From what I gather I think you want a larger bolder dynamic sound - that's why I think you'd say that - not that the u52 is not so. And so I think you are really going to like the WA5 or Glenns 300b based amps.
The 274b does not make me want to "replace" the 422a - they are both very good. And the metal gz34. These three are my favorites and the u52 pretty close too.