I built this up back in January, a 6AV5GA SET, with 12AT7 SRPP drivers. These could also use 5965s, 12AV7s, 6414s, 0528s, or 6072s, all easily interchangeable.
All the grim and gory
details of my build are posted here:
http://diytube.com/phpBB2/viewtopic.php?t=4576
Since the SRPP tubes already have 12V filament capability, it would be a breeze to use 12AV5GAs - I have several of these whiich I recently bought off e-bay, and they are the same tube, except for the filament voltage.
6SL7s / 12SL7s should also work very well in SRPP, as would 5751s.
OPTs are 3K:8 10 watt Transcendars, though these are essentially made of unobtainium today, they are excellent. an equally good choice could be the One Electron UBT-3, or the James 6112 or 6113, using the 3.5K primary connection.
This amp really exceeded all my expectations, by a large degree
Stepping back to an earlier version, the original 6AV5GA G*S*G:
Its predecessor is a modified G*S*G, which works well with the 6AX5 rectifier, and even better with a plug-in solid state rectifier "replacement" (built into an octal tube base, with two uF4007s, with a 50 ohm, 5W WW rsistor in series with each anode) which delivers higher B+ and lets the tubes reach their true sonic capabilities. Details here:
http://diytube.com/phpBB2/viewtopic.php?t=4551
/ed B