Output Tube recommendations for Thor TPA-150 Amp

I am an owner of thge 150 watt monoblocks built by Paul Marks, President of Thor Audio which has recently gone out of business. I currently use 8 El-34 output tubes and wish to know has anyone tube rolled and what do they believe provides the best sound. Another brand of El-34, I believe mine are SED Made in Russia and are El-34's. Anybody switch to another tube, and if yes what might be better and
compatible. Mine are coming up on 2000 hours and am getting prepared to replace. Also do I replace at a certain point or wait for failure. These are questions I could have asked Paul Marks if he was available.
If you are interested in experimenting I would see if amp can be wired fore KT-88s because I cannot say enought good things about the reissue,Sencor,
Gold Lions.
They are not cheap! The easiest choice and the type I use is the JJ E34L in blue glass. If yo like a very dynamiv slammin tube, try the EH 6CA7s . I am no fan of Russian tubes but these are excellent. If you are flush I have noted more than the usual matched quads of Phillips/Muulard tubes.
If you cherish bass see how the JJ KT-77 works out they are carried by "eurotubes.com" .
I own the TPA 30 and have tried a few including cryo el34 SED quads and always come back to the Regular SED EL34 quads..For my money they are the best bet...Also I wouldnt wait until you have a tube failure,,Be prepared..You should always have a full set on hand for back up...