I have gone through the numbers in a similar exercise to try and pick one. Dimensions on the Kata-bags website (eg 3N1-20)
Video bags camera bags Kata - Manufacturer of camera bags
In the 3N1 the body sits against one side at the opening with the lens across the bag for 'quick draw'.
The K-7 with a 50-135 is about 21cm from the LCD to the filter with hood reversed.
Internal dimension of the 3N1-10 is 19cm across (so no it wont fit) 3N1-20 is 22cm across. 3N1-30 is 29cm across (so this might even fit the with the hood mounted?)
The depth if the bag internally is 16cm on the 3N1-20&30 is 16cm and the 3N1-10 is 15cm so i assume this suits the K-7+grip. This depth would also suit the 16-50 and DFA100 "on end".
Plenty of room for the flash at the position they show in the website video.
I would think to get the larger versions 20 or 30 if you want to have the 50-135 mounted.
Not sure how you could pack in the 50-135 which is about 15cm long into the 3N-10 off camera.
If you are thinking to get either a 60-250 or DA300 in the future then only the 3N1-30 has the width.