I doubt very much if it would be in one piece Oskar. Probably a combination of your other two choices, big pieces, small, pieces and small parts. Even tourist, bottom of blue lagoon aircraft wrecks have bits broken off and parts scattered about. The Niku reef slope/seamount is causing problems with the kit being deployed on this expedition, a good indication of how inhospitable it is, 45 to 90 degree slope.
The scenario is that the plane was swept off of the reef flat and got chewed up on its way down. Add to that the erosion and corrosion of parts over the years, especially those that hold other parts together, once they go the parts they hold together will obey gravity and head down the slope. Heavy gear like engines will place a considerable strain on decaying superstructure especially significant on a steep slope.
Electra is the hope but, at this stage let's just say aircraft wreckage for now and, remember planes are constructed to be strong and light weight where as cargo ships are built to be strong and, well, strong.
IMHO of course