There was no manual disc brake option on '69 roadrunners, however in 1970 there was a manual disc brake option on B body Mopars for taxi cabs. This is a standard disc brake master cylinder of the era with outlets facing toward the inner fender, with the addition of a pushrod and mounting studs. There is an aftermarket version of the MC available, Raybestos MC36283. You'd need a pushrod and mounting studs, which should be fairly easy to find used. As for the mounting, there is a mounting plate that goes on the firewall. I assume the one used on manual disc is same as that used on manual drum?
If original appearance isn't important, Dr Diff probably has a setup available that uses a late 70s early 80s Mopar master cylinder, adapter plate and adjustable pushrod ready to bolt on.
