The 6dn3 is to mitigate power on current so no benefit to rolling. You might consider NOS Tung Sol 5881 for the power tubes. Get a nice pair of 12au7’s, perhaps some old Mullards or Brimars, it all depends on your tonal preferences. Perhaps even some nice RCA Command 5814a’s for a little more neutral presentation. Get a nice pair of 12bh7’s, NOS GE’s aren’t terribly expensive. Those tubes should be matched and I’m not sure how you ended up with the odd pair in that position.
For the price of those blue glass el34’s they better be good. I also believe Jeff Day recommends tubes that are widely available rather than the best sounding. Just a guess. I think the best sounding tubes are the ones you roll and choose based on your listening preferences. There are many, myself included, who believe the NOS GEC Genelec KT66 is the power tube in that amp that makes you question whether investing another dime in audio gear makes any sense. It’s that synergistic and that good but they are pretty rare.