If you go with telefunken 6DJ8/ECC88's from the early 1960's or late 1950's, make sure that they are original's and not fakes. The originals have the Telefunken Diamond symbol on the bottom 1/2 of the tubes. Other good tubes are the HOLLAND (Heerlen Factory) made amperex non-Aframe versions with the small or large Halo getters from the late 1950's to very early 1960's. There is a difference in sound between the large and small Halo or "O" Getters with one have a little more air and being a little more musical but I can't remember which is which since I have not used them for over a year. These tubes are warm and airy with deep bass. The Tele's are more well rounded. Stay away from the A-frame versions as they are very forward sounding and not as refined.
Here are a pair of NOS NIB original Tele's like I mentioned above-
2 Tubes Telefunken ECC189 6DJ8 ECC88 Diamond 11011 from 1963 | eBay