it looks like you need the second, as that is the one that is detailed the best. I would check the positions of the doors and windows first, tough, because those seem to be radically different in comparison with the original one.
I needed a Royal Navy Merlin to my HMS Bulwark so I took a look at this sheet of the two Merlin's. But taught by experience and good criticism from all of you, I've checked the measurements. They weren't accurate enough
I've made a box with the right proportions and redrawed a Merlin in the Royal Navy configuration
If you think it's all right, it would be a pleasure to have it in a helicopter parts sheet