Both would be able to take what the other could offer. I doubt Briscoe is good enough to beat Walker on points. Walker to outwork Briscoe to a clear UD.
Walker's pedigree in being able to compete with the heavyweights virtually insures that he would have never been wiped out by any middleweight or lightheavy for that matter, although styles do determine fights in unique situations. I think there would be very lttle to seperate Walker and Briscoe except bulldog tenacity and will to win. They would be a great twosome on par with Gatti and Ward, though on a much higher level. I wouldn't have been surprised if they were to have had a trilogy between them with Briscoe winning one and Walker winning two, with not a razors edge woth of difference between the two.