I do have a WWII era military rectifier, but prefer a somewhat later GEC cup base U 52; I run a set of GEC KT 66s that I bought NIB NOS some years ago for my "vintage" system. Most of the tubes in my two systems are somewhat more modern- 6h30s from the late ’70s. I don’t know how old the Russian 6C33C I use in the Lamm amps are; I suspect they are also late ’70s. Those mercury vapor tubes are very cool, but have not used them.
I recently retubed the main system but have been having some noise crop up- I think it may be the line stage (Veloce Lithio upgraded by Vytas)-- last time I had this issue, I cleaned the battery contact plates and the noise disappeared.
I’ll sort this out soon, I just need time and patience since I have a full complement of fresh tubes for the Lamms, along with NIB old stock Tele 12ax7 ribbed plates, which I prefer for these amps- they give it a little "grit" which makes them less sweet and lends a gravitas to the amps. I run them with extremely efficient horns.
Trying to locate a matched quad of early production 6h30 reflectors is not easy or cheap; to my guesstimate on hours, they should still be in good fettle, but we’ll see.