Okay, after a bit more burn in and considering/testing the options, I've decided it would be best to optimize the LD for 6SL7's.
I've got another desktop amp that's built for 6SN7s so those will go there. It's not balanced but has a separate power block and point to point wiring.
Next up I'll be ordering the replacement Mills 330 ohm power resistors so to get the anode/cathode resistors at the same time would make sense. Are they the small ones near the front of the board?
Also got some Wima MKP4 DC Link 500V 100uf capacitors (part nr. DCP4H161007J ) to try out as decoupling caps. Haven't used 4 pin capacitors before. What would be the correct way to connect/solder those - is it to first connect two pins on one side (as in this photo) and then add a wire from the connecting wire to the cap positions on the pcb?
(Photo taken from Klipsch community forums)