I used the CSRP K-B disc brake conversion. It's not that expensive (mine cost $524), installs easily and is compatible with a stock Ford unit from that era.
I am almost finished converting my '67 six cylinder, and if I had to do it again, I'd buy a complete running Ford Explorer and use the motor and rear axle from that. I'd also find a used T-5 and rebuild it. In fact, once I'm done with my convertible, my plan is to do that very thing to a '67-'68 coupe.