My question is why? A very-good valve amp is a very-good valve amp. Monoblocks is fine, but in reality it's more cost, more space, more valves to roll, etc.
With your budget I'd go about it differently. The below amp can be picked up new for around £2200. Until you start spending a vast amount more there's little that I've heard in the valve amp domain that's better. You can then further 'upgrade' this by sticking an excellent preamp in front of it (they have a pre bypass mode).
For £5k you've then got a truly kickass system. I'd then also roll the valves in this. However, you've got a lot of change from your budget to do this if you go this route.
My comments are not speculation btw, I've heard this exact amp in three different systems and it is utterly excellent. Especially considering what it costs.
I've also heard valve amps that cost 5x this amount and they don't sound 5x better.
ATB
This interesting new mid-price Chinese valve amplifier gives Mark Gusew a warm glow…
www.stereonet.com
Edit: if you get the chance and are in the UK you should go to the Maverick Hifi show. There's a post on this forum with info about where and when. There will be many valve amps there you can hear for yourself to get some inspiration.