On mine, i did it slightly higher, but not much than exit.
What's bellow the link between the two acts kind of a single bell.
For example, if you had two bells next to each others, one low entrance in the first bell, a link between the two, on top, and a low exit, the first bell would vaguely act as a bell, but more like a chimney, and the second like a downdraft tube.
Add a bottom link, while retaining the top link, you have a single bell, with a wall inside.
Best practice, is link at the bottom. . But there is also a matter of practicality. If it's not easy to do, a link between the two, higher than usual is fine.