A: Yes it should as dimensions are 4.6 x 4.1 x 6.2"
A: Hi, Andrea! Regarding your question about the Lowepro Adventura SH120 II - Black: No, the internal dimensions for this case are 4.57 x 4.13 x 6.18" the dimensions of your b600 are 4.8 x 3.3 x 4.0 " so the case would be too small for that model. If you have any additional questions, please do not hesitate to contact MyTGTtech at 877-698-4883 every day, between 7am-11pm CST.
A: The T6 with a 75-300 ends up around 8" long and the bag interior is about 6" deep. It may fit as the top is adjustable, but I recommend you try it first.