Kays are a pretty standard size basses and will fit into a regular 3/4 case of most brands. I don't know about bobelock specifically but I've had them go into both gollihur and mooradian bags and fit very nicely.
I just received a 3/4 Bobelock bag for my 3/4 gamba Pollmann. My previous 3/4 bags were quite generous sized, but the Bobelock is a very snug fit. I'm very satisfied with the quality for the price. Quinn Violins is very good to deal with. The bag was drop-shipped from Bobelock, so it had farther to travel than I expected(I'm fairly close to Minneapolis). I would make certain that you could return it if necessary. My only complaint is that the side handle is a little bit too far down the side. Someone else mentioned the same thing.
