narrow side holes are 52mm (2 in) centers and the long side is 92mm (3.62 in (3 5/8") centers.
alternatively, get yourself a chunk of metal, drill a couple holes in it to mount it over your cabinet hole... take a sander to the face side edges to round everything off a bit... and then hit it with some black textured paint like some of that rustoleum hammered finish coating. it's about all they send you as a blanking plate for filling holes like credit card readers and bill acceptors.
use "carriage bolts" that you've sanded smooth and paint matched to your chosen finish to mount your plate for that supposed-to-be-there look