71 Chevelle brake conversion

I'm helping a friend put a front disc brake kit on hit 1971 Chevelle convertible. He's got all the main hardware that he needs to get them on the spindles. Our question is: does he also need to change out the master cylinder and proportioning valve, and if so what vehicle's parts would work? Thanks for any help.

The stock spindals need to be modified. Yes you need a new master and valve plus brake lines. Check with the http://www.getdiscbrakes.com/rightstuff/Default.aspx