Considering my experience with the big S265 Peerless output, I'd conclude that a single 16277 would be a similar performer. Better than the cheaper integrated options you mention I'll bet. Get one, unwind and make more. No big deal there, that's for sure. Probably ~$75 each to make as many as you want. Can't call that expensive...:) Or try building with a 16311, or 16309.

I would agree that the W2 would do quite well with its own 6L6's. I don't have much experience with EL84's. 6L6's, those I've built with and liked the result. I would say that the original front end can be improved upon easily. See Merlin V2 for an example. Getting rid of the global NFB path has always sounded better, assuming the rest of the amp could be brought to heel of course...:)
cheers,
Douglas