Joan Taylor as written a fascinating albeit short article on Jesus' physical appearance. In order to read the whole thing, you'll need to register with ASOR (free). Among her many interesting points, she argues that Jesus' long hair is probably a mythological addition to his legacy as are his flowing robes. We'd be closer to the mark imagining Jesus with short hair and with a sleeveless tunic. Or, in other words, Jesus looked more like high-school Chris Keith than high-school Anthony Le Donne.