Brakes locking up.

A few years ago I bought a front disc conversion kit from Mancini Racing and installed it prior to running with my rebuilt /6. At some point when initially running with the new motor the brakes seem to heat and stick while driving. The only way to relieve pressure was by cracking the lines open at the master cylinder. I have been doing a lot of other things lately to the car and am now trying to tune it again. The car seem to run okay prior to bleeding the brakes and after bleeding them they seem to heat up and lock up. So bad that it will sit in drive and not move. I considered making a heat shield for the master cylinder because I have wrapped headers. Does anyone have any ideas as to why this might be happening?

This problem needless to say makes it much more difficult to tune the car haha.