That part number sounds like the 1/4" locking jack. Headroom uses the all black, XLR and 1/4" combo jack. It's available in board mount and chassis mount. A bit harder to find for sale than the 1/4" locking jack, but it is available somewhere
I put a 1/4 jack in the back panel of my Corda, but the Neutrik won't fit as space is tight there. The front panel has other problems. The face plate is quite thick to drill, and the board has to come away from the front panel so everything there is attached to the board not the face plate. There isn't room to do a board mount there for another jack.
Yes, that darn stator nut. You may be able to tap it off, worse case you can drill it off with a dremmel tool, but either way be careful not to scratch the front panel.
I don't see any way you could mount the 1/4" locking jack on the Corda without removing the two mini jacks. This might be the best solution. If you still want to have a 120 ohm and a 0 ohm jack, simply get a DPDT toggle switch and wire it in place of the outputs