Ivamorten,
What I'll say has been writen before in this thread but I'll recapitulate and provide some personal spin.
I have found that Chardonnay takes some time to break-in. Let it break-in for a few months with the stock tubes. This will stabilize the sound and acclimate you to the tubes that Mick voiced the preamp with. If you still want to roll, now you have a baseline.....
I've rolled many of the tubes mentioned on this thread. I highly recommend that you find a reputable tube dealer that will provide good tubes. The Chardonnay is very transparent and 'deserves' the best! I've wasted too much money on 'fleabay'. Caveat emptor!
Tube rolling is system dependent and I like to think of it as the bass/treble controls or system equalization. A given set of tubes will provide a very different response in your system. For example, a bendix 6106 rectifier will sound different with the Kt66 vs a bendix with a set of Tung-sol 6L6s.
For my particular set up I like the 6106 over the metal base Gz34. I like the 6F6GT in the regulator over the Kt66 with the 6106. However, the combo I've settled on is the 6106, 350b in the regulator and the Tung-sol 6sn7gt.
Enjoy the magic of Mick's preamp and save some money for your music!