Yes. It'll be an 8 foot long tank and at least 36" wide.
That would be pretty cool.
How do Aros (black or silver) get along with CA/SA cichlids? I've heard mixed things. And I'd rather have cichlids than aros.
Not much an issue with large aros and cichlids. When young(under 12") cichlids can easily overwhelm and overpower the arowana. I would recommend the arowana be at least 2x the length of the cichlids once it reaches 12".