Langrex has some Winged C Svetlana tubes that are sold as quad matched pair and sound good. I ran these in my Air Tight amps with great success. I would also second the Gold Lion KT77. Jeff Day at a positive feedback likes the Sophia EL34s in his Leben but they are pricey.
Word is that the 6L6 might be interesting too, assuming you have a CS600.
Word is that the 6L6 might be interesting too, assuming you have a CS600.