I've got lots of hours on the old -100... no greater bird in the sky.
Anyway I don't have the Boeing 727 Mx Ref. Man. on this computer to send you a graphic. But the the initial actuation of the cargo door on the -200 lifts the door out of it's sill about an inch before opening outward. True on the surface the door does not appear to be a plug type door, but per Boeing's descriptin it is.
Next time you fly the jet check it out.