With all the dividers removed the interior would be about 9 1/2" x 7" x 4 1/2". But the way the bag is carried and the dividers fit, I'm not sure you'd want to carry a camera/lens that way, even if it did fit.
Although I don't have the battery grip to verify I did check the clearance. You have a couple inches of empty space between both the top and bottom of the camera body and the sides of the bag. It should fit.
I have the d5300 with 18-140 lens and it fits perfectly. Could accommodate 2 more smaller lens but not sure about the 50-300. Might be too long for the depth of the bag. Love the bag though especially for travel.
I just got the 102AW and the depth of where the camera would fit is @ 7". That would be the total length from the camera viewfinder to the end of the lens.
The side lens pockets themselves are only @ 4 1/2" deep.
I might be a little conservative, but I tried to measure accurately. This bag is really small. A lot smaller than it appears in the photos.