Andre S.O.G. Ward would have given prime RJJ FITS and outpoint him 10-2 / 9-3
Too slick, too much infighting/outfighting ability. The only 168er I imagine COULD beat him would be Joe Calzaghe but that's also a toss up. Calzaghe/Ward would have been a great great match.
Ward would never stop RJJ (Prime) but he would outpoint the hell out of him. Too much head movement, too fast, too much lateral movement, would have taken RJJ's left hook/straight right out with his skills, iron chin.