I'm amazed that so many people can't believe some guys have 6"+ girth!
6" girth is by no means ridiculous and, to be honest, if you're a guy laughing at the thought of it then it's probably not saying much for you. Think about it...
To the OP, I'd say try Trojan Magnum XLs. They're the widest you can get 'over the counter' (Boots, etc.) but are still not great for girth.
I've also tried some of the specialist suppliers and agree with what someone said earlier about length always seeming to increase at the same time.
I'm 7"+ in girth myself but only(!) around 7.5-8" length and it seems that the manufacturers don't think that's long enough for the widest ones!
I think you're (he's) just going to struggle, to be honest. There's nothing out there that will be exactly what he needs.