How would a man dress in Ancient Greek or Roman clothing as a costume for a fancy dress ball or masquerade ball in the Regency era and the early half of the Victorian era?

One of my favourite styles of fashion in the past, are fancy dress and masquerade ball costumes and one thing I’ve been wondering about recently, was how Ancient Greek and Roman costumes were worn by men during the Regency era and the early half of the Victorian era.
Because of the fact that most male costume’s I’ve seen, all have pants and I can’t for the life of me picture how you would dress as a convincing Greek or Roman god, while wearing a suit (because they didn’t have Percy Jackson and the Olympians series at the time to be fair).

Any help you can give me would be greatly appreciated.