Build the linestage in little larger chasis (enough additional space for two SE OPTs and two tube sockets), with overdimenzioned PS (additional DC current say >120mA), with B+ about 300V. Choose OP for the 5687 a little higher (15-20mA, Ugk=4-6V, Uak=110-150V), CCS load.Then we can build line stage first, with amplification about tube mu, or 17. We can use it for (pre)amplification of low-signal sources (hundreds of mV) to "drive" power amplifier.
But, our linestage can be a good "driver" for SE tube amp with CD player input - 2Vrms, say for EL34 in triode, or even 2A3/6B4G.
Once "armed" with experience building line stage, additional work for SE output stage would be trivial :-).