Sorry no pics as my cam and my photography skills are both crap but I have a Florida gar who's nearing 18" with a couple of 6" severums and they're doing well. The gar/cichlid combo is usually advised against around here but I've had no trouble so far with my peaceful cichlids (sevs and chocolate).
I think the sev + arowana thread in the arowana forum has some pics of sevs with arowanas and gar.
I think the Severums would get beat on pretty badly. They may be a little to colorful and peaceful for the gar to resist. It could work...just have an extra tank ready in case things go south. Your best chances would be with a Florida/Spotted gar...my Tropical would not tolerate them though. It's really going to be a hit and miss combo as many combos are.