G3 seems to show evidence of constructual changes from its very early days, right up to the down tools situation that we see today.
I dont see the increase in size being a later date, but one of an incorrect reading of the master plan that Giza was built from, so im going with the cock-up scenario by the original builders, that is so evidently shown in G1's and G2's miss placings, its as if my master planner of Giza only appeared on the scene to point out the builders mistakes .
The granite casing , for me thats restoration , you wouldn't buy a ford mondeo and have it resprayed in gold paint, so why would you build a third rate pyramid and clad it in the finest stone . but if you just appeared on the scene and found a ready made pyramid with no name attached to it then by cladding it in a new coat of granite you could convince those that came after you that that pyramid is yours.
There is another curious aspect of G3 that resembles a similar structual design of G1, and thats the concave affect of its sides, G3 also shows this concavity affect on certain times of the day, there are aerial photos of this affect, but for the life of me i cant find them right now, i beleive Scott Crighton put a photo of it some time ago, so what im suggesting is that there may be a direct link to the builders of G3 and G1.
Then there's the Mortuary Temple, a lot of restoration seems to have gone on there, but there are some really big blocks in its construction that seem megalithic in nature , and then there's the butting up against the side of G3 that shouts out restoration of a later time, so all in all G3 has gone through more than one owner.
Heres an interesing Youtube video of G3 and its outer casing masonry and Mortuary Temple.