[Robert Gribnau]

I suggest that you try out the input stage and phase splitter using the original values first (so 180K instead of 100K, only 470 Ohm in the cathode lead of V1a and 15K for the feedback resistor; what is at the grid of V1a can stay like it is now). If that works OK, you can always try out modifications.

You could try 270 Ohm instead of 330 Ohm for the cathode resistors of the output stage. See page 58 of the book I linked to in post #8 (B+ on the centre-tap of the output transformer there is 317 V so as long as you don't exceed that the PCL86's will be fine; see page 62).

Filaments should have a proper path to ground. When the filaments are being fed from the same transformer that provides the B+, than there is some capacitive coupling between the filaments and the rest of the amplifier (that's probably why you get away with it now) but good practice is to ground them properly.