In your situation where you'll need 12 matched tubes my advice would be to contact an experienced, reputable dealer for a recommendation within your budget. I've had great luck buying from Jim McShane.
I have a Cary Sli-80 F1 and have tried a lot of different tubes, mostly El34s. The Gold Lion KT77 matches your wants, I think, and has been a very reliable tube for me but the're about $90 a pair. The best bargain tube I've found is the 1980's Russian military 6P3S-E, which is a 6L6 type but you would definitely want to get them from someone who can test and match them. McShane sells them for less then $40 a pair.
I have a Cary Sli-80 F1 and have tried a lot of different tubes, mostly El34s. The Gold Lion KT77 matches your wants, I think, and has been a very reliable tube for me but the're about $90 a pair. The best bargain tube I've found is the 1980's Russian military 6P3S-E, which is a 6L6 type but you would definitely want to get them from someone who can test and match them. McShane sells them for less then $40 a pair.