Have Mikey at Magnequest make you a B7 that is 10k:10k. Use that at the input after the attenuator. Run a single Quickie circuit on the other side of the 10k:10k, then use a 5k:5k B7 as a parallel feed output transformer. Mikey could also provide a suitable plate choke, or the PJ CCS could be used as a plate load.
Constructing a differential circuit with the 3S4 will work and produce sound, but I have absolutely no doubts in my mind that using input/output transformers and a single ended circuit will sound better. (I have tried this many times myself)
-Paul