Nope, the Russian tubes generally much, in fact much worse than western equivalents. There were however some exceptions. Those options were due to various reasons. The tubes like GM70, YO186, 1P24B, 6E5P, 6N30P, BO188, GM57, UB180, 6C33C, 6N6P, M457, ТО-143, YO104 were very-very good. The GU81, GU48, GU29 were generator tubes and they are presumably OK; I did not hear any good-made amps with it. The GM70 is transmitting tube as well and it is exceptionably good tube also, way more superior then 211/845 tubes but it is kind of not used yet tube as no one so far made any decently sounding amp with it, at least among those that I heard. So, the Russian transmitting tubes from the GU line might be fine tubes. To make an amp with them is a totally different subject…
What surprises me however is why you have expressed an interest in the high power tubes? You are with horns and even you LF sections have over 100dB sensitivity. What will you do with 120W SET?
Anyhow, I do not have a circuit for this type of amp. The circuit is not a problem, to know how to get sound out of those tubes is the problem and I have no knowledge about it. In the world of transmitting tubes the tube never was a problem. The right output transformer is the problem. It might be VERY expensive to make it properly and it might be very unnecessary due to the existence of DSET concept. Still, to hear a 120W SET over a few days might be a fan experience …The Cat
"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche