The Peerless catalogs state that it can be used single-ended or in PP, but was designed for parafeed. (However, people on this forum have noted that many of the UTC transformers specified for either SE or PP don't sound that great when used one way or the other - SE, I think it was - so YMMV). You don't have to use the feedback winding if it's not needed for whatever you choose (ground it if you don't use it). But keep in mind that you can only DC couple it in PP (as in the EQP-1) where you can trim out any imbalance between the tubes (it takes 0ma unbalanced DC).
With a 12,500 ohm nominal primary, you could try it SE with any cap coupled 12AU7, 12AT7, 12BH7 etc output stage and see how it sounds. Of course, that primary should also work with SRPP or WCF stages as well (even if not ideal, impedance-wise). But I wouldn't think it would sound that great in PP without the feedback winding. Normally, you'd expect a 20k or higher nominal primary impedance with PP 12AU7s or similar tubes for low distortion. The feedback would fix that. But global feedback is tricky unless you're copying an existing design. (Although that shouldn't necessarily scare you off from trying it w/feedback, depending on your experience and willingness to work through any issues that might arise).
At a +20dbm max level, it's a little too low level to use for a classic varimu compressor build (e.g., using PP 6V6/6L6 etc, though there are a couple of designs that use 12A_7 type outputs). So your best bet is probably a mic/line amp, taking the above considerations into account.
If any of this puts you off, you might just consider selling it and buying something else.
Just my 2 cents, thinking out loud.