how many cruisse missiles fit inside h6 depend on the cruise missiles themselves. We dont know the insides of h6k's weapons bay but we do know the dimensions of the bay in the latter versions.
it is interesting that when we look at the images of earlier versions of h6 we can see that the bomb bay door are some 6,2 meters long. When we look at that new image of h6k we can tell that the bomb bay door is 6,5 meters long.
Using the images of the bomb bay of the original versions we can thus say the bomb bay is 6,2 m long, 1,26 meters wide and 1,25 meters high. (height to the beginning of those bomb rack holders is 0,91 meters, though centerline height is over a meter)
So it really depends on the type of mechanism and the missiles themselves. Maybe current missiles wont fit, maybe future versions will. One could, for example, fit 3-4 tomahawk missiles in a snug fit rotary launcher in such a bomb bay. (3 to 4 because im not sure how well the rear fins fold and how much do they stick out)
H6k's bay could be broader. Not the doors themselves but the insides. when one looks at the image posted here it is evident one could get extra ten or so cm on the sides of the bomb bay. doors themselves are 1,5 meters wide. it is the internal equipment and the ladder-like structures that make the bay more narrow than it is.
