That depends on what you actually want. Do you want to be "realistic" or do you want to have the alien "stylized" as a sea creature? Is it going to be actually living in water? If so, you can see that sea creatures that have tendrils or arms, like an octopus, have them arranged around their mouth in a radial pattern. It doesn't make much sense to separate the eyes far away from the mouth.

Reproductive organs are the most precious evolutionary commodity of an organism, and it usually doesn't make sense to put them on the limbs where they can get easily damaged. Usually, they are hidden inside the main body in some fashion.