However, it's not about direct alignment. Too much emphasis is about direct alignment. Most portal tombs face due-east, so they're bound to align with at least the equinox sunrise. More study needs to go into what other alignments there are from the site in the way of notches & peaks etc.

Proleek was rebuilt and so its true alignment is uncertain. It's also a tough one to determine which way it faces. I have it in my head that the front is east facing and Sleive Gullion is definitely to the northwest.