I would suggest RCA clear tops if you must spend on NOS. Alternatively there is nothing wrong with JJ ECC82S (the short plate version). Both have well extended treble without being too warm. And yes, the Chinese 12AU7 tubes can sound decent if you can find quiet ones. The JJ ECC802 (long plate) I do not recommend as they tend to be very microphonic (plus they are warm, not bright sounding). Some of the military versions of the 12AU7 are nice sounding, such as the 5814A and they are VERY well made; Kevin Deal has good ones normally.
I am not sure how much change you expect, but it will be quite small and is like adding a little seasoning to your food. It is not night and day and will most likely not compensate for hearing roll off. You may want to think about EQ of some kind.