Hey path09en, I don't know much about the new tung sol (the NOS tung sols are among my favourites) but I can tell you about the tubes you have.
The chineese 12ax7 is a well made, quite, very high gain tube. When I got my Two Rock SIG it was FULL of them. They are a little bright and very articulate.
The ECC83 looks a lot like a JJTesla but I can't be sure. If it is a JJ the are well know for the good mids and balanced response. Not the most exiting tube in the world but it will sound good and be there for you at a reasonalbe price. In fact, one of the best 18 watt clones I have heard was loaded with these and JJ EL84's. It sounded fantastic.
Like Ripper said, you need to swap and listen and swap and listen and swap and listen.