I punched out the hole in the chassis and installed a 6SN7 from the start. I wouldn't recommend this method for a first time kit builder but if you have a little experience it should be pretty easy. You can see my thread here. http://bottlehead.com/smf/index.php/topic,1222.0.html Unfortunately the photos that I posted are gone now. I did use an adapter to convert back to 12AU7 for comparison. Lets just say that I'm glad I wired my amp for 6SN7. 
YMMV.
It was actually your thread that got me thinking about starting off with the 6SN7. I have some experience with point to point kits and tube work, so that's why I asked.
Perhaps the quality of the Chinese adapters would be better than some of the early threads that mentioned the introduction of buzzing. It would probably cost me less to build the amp stock then purchase an adapter. If I encounter issues, then I can work on constructing my own adapter.
One step at a time... and I haven't taken the first step of ordering the kit!
