Here is a picture of it with the cover off. The pin that holds the coupler in is on the coupler box cover. I put a mchenry there for size reference. If opening up the EZ mate a little during operation won’t weaken the coil springs, then I might just force couple them together and them like that. It looks like a standard size Kadee whisker would be too large to just do a drop fit.
It almost looks like the swivel thingy that carries the coupler is big enough that one of the Kadee boxes would fit on it. The 714 definitely would and as I noted, the way its spring functions acts a lot like how the kinematic is said to act. The 714 spring may not have quite the travel as the kinematic, though.
Anyway, here a side by side pic of a Kadee 148 whisker couple next to what I think is a McHenry (or a very near clone0.
So the 148 is actually smaller in several ways than the McHenry. The back part of the shank isn’t as wide as the McHenry. The 148 shank is shorter, although Kadee does offer long options IIRC. The knuckle is smaller, so may work better for that reason if coupling to the Kato cooplers that don’t nest as easily with the McHenry.