69 dart disc brake conversion with 14" Crager SS rims

So was about to do this conversion, but from what I have been reading and been told this is not possible. PirateJack (which sells MBM) says it will not fit. Still waiting to hear back from Doctordiff. Has anyone ever successfully done a front disc conversion with the same setup? Worst case I will just go powerbrakes.
Thanks
Last year I did a front brake disc conversion using a kit from Summit, SSB-153. Can be small or large bolt pattern. The kit had everything that was required to do the conversion including the master cylinder. It also works with my 14" SS cragers. Was fairly straight forward and easy to install.