I have another idea to share with you, a tube mixing strategy that I learned from a consultant at the Audio Outlet/CSA Audio, Mike O'keefe.
Put your NOS tubes in the first line stage socket (front of preamp to the left) and use two more widely available, and likely less expensive, tubes in the second and third sockets. Try the Telefunken matched with two Electro-Harmonix, an Ei with two Electro-Harmonix, or Telefunken and two Eis. Each combination will change the balance somewhat but not the character of the unit.
This system also works for the phono section. However, the NOS tube should be placed in the last socket at the rear of the unit. I have used this strategy with great success during my re-tubing of several Jadis preamps over the years. It is a cost effective way to listen to different brands in your unit before making a significant financial commitment!
With regard to the power supply, I have used GE, Mullard and Telefunken 6CW5/EF-86 tubes, and Ei, Mullard, Electro-Harmonix and Telefunken EL-86 tubes in the power supply with good results.
Good luck!