See my edited post above with the pinouts of the two tubes.
Going with a 12AX7 does give you more options if you want to try different brands or some of the new production versions.
If you're going beyond a simple change from 6EU7 to 12AX7 you should remember that the changes Dave made are based on his decision to replace the output transformers. That decision was made because the stock output transformers were designed for use with 4 ohm speakers and he found that they performed very poorly when more common 8 ohm speakers were used. If you decide to keep the stock transformers some of those other changes may not be appropriate. You might want to ask about that on his mod thread. If you decide to stay with the stock OTs you should be using a 4 ohm speaker load - either one pair rated at 4 ohms or two pair of 8 ohm speakers wired in parallel.
My recent conversion of one of these amps to use 12BH7 output tubes allows the use of the stock transformers with 8 ohm speakers. I'll be updating that thread soon.
http://www.audiokarma.org/forums/in...0-or-8600-conversion-to-12bh7-outputs.824135/