First off, do you like the presentation of your CJ gear? If so I would strongly recommend upgrading parts and by ALL means replace the tubes with NOS. Andy of Vintage Tube Service is the guy to contact for tubes and is familiar with CJ. Upgrade services by Bob Backert , Bill Thalmann of Music Technology (highly recommended from personal experience), he is a former cj tech director and understands the designs and philosophy of Conrad Johnson and of course Jeff Fischel of Conrad Johnson, less flexibility and definitely a bit more expensive.
There is a lot of music in those vintage pieces, more than you might realize. Their preamplifiers are definitely among the top of the heap, "just sounds right" rings true. Agreed, there are good modern tubes, maybe even cheaper in given instances but NOS is a sure bet with CJ though a bit more dough.