I like the placement of the ray cannon. The problem with having it be held by one of the tentacles or a separate pole is that it could get shot off easily. Mounted on the main pod and possibly mobile? Makes more sense from a design perspective.
Needs a heat ray generator held aloft by a tentacle that can be directed towards the target, the heat ray never came from the side of the body from a fixed source. That's the trouble with directed-energy weapons, you need to point them.