Excellent question. I'll keep my eye on this thread.
However, I encourage you to put the idea of tube-rolling your amp out of your mind for a while. Enjoy that sumbitch the way it is, 'cause it's gonna be awesome. And constantly obsessing about what to tweak and what tube to roll might only lead to more questions like "have these new tube burned in long enough?" or chin-stroking in order to be able to declare that some other tube is better.
I'm pretty sure that the the WE's would sound different. Probably better. There are many options out there. Apparently, most of them are excellent. But there are more 300B tube options available now than ever before in human history (can you imagine that!?) and nobody that I know has reviewed and compared them all. At most, they've compared a few and arrived at their own conclusions. But the human mind has a way of impacting our perceptions and rationalizing our thinking to protect us from feeling bad. I'm not saying others are wrong in their assessments of the various 300B options. I'm not saying that more $$$ doesn't buy better performance. I'm simply suggesting you've got a cool new amp and you should enjoy it without distracting yourself with "what if this tube sounds better" kinds of questions.