I believe we covered this just a couple of days ago.
One more time...
A pair of 6L6 will work just fine, I've done it with several Sano's & no complaints.
With the self bias mode, you may find bias current runs to the high side. You might bump the Rk up to 250 or 270 ohms 10W, otoh that may show you some obvious crossover distortion as you approach the power limit. Also no point in chasing every last watt, these really turn out more like 25W at clip, in spite of the product designation.