I would recommend Gold Lion's.
I have not compared directly to the Gold Lion, but the 12AU7 is one of Mullards finest. It is one of the most rugged tubes and is very good sounding. (very long lasting) For the 12AX7, I think you would be OK with one of the new production premium tubes, they seem to get good reviews. I have seen pairs of Telefunkens pop up here on A-gon from a Canadian seller for very fair prices though and might be about the same price..
Yes certain NOS tubes are very good and well worth the price. The Gold Lion's are very good current production tubes and are very reliable. If you were putting them in a premier 16 or 17 then I would say give them a try. But the PV-12 is designed to such a level that it isn't going get the most out of NOS tubes IMO. I have used NOS Tele's in both my Premier 17 and 16 II cj pre-amps and they are very nice tubes. The Gold Lions are a nice upgrade to the more pedestrian current production tubes while still being reasonably priced.
when I owned my CJ 12 iI used 60s vintage Philips/Amperex and for a change RCA cleartops. Ecc82/12AU7. The ecc82 & the 12AU7 are the proper tubes to be used. The tungsrum are also a real nice tube to roll with this guy also. Mullard were too much of lush thing for my tastes. If you do like the mullard, may want to consider the Brit made brimar also. Regards, Dave