He's going to have to sort out a pushrod and linkage for the brake pedal to the master cylinder. And get mounting studs for mounting the master to the firewall. There may be a different backing plate for manual vs booster mount for the firewall?
The linkage parts for a manual drum setup would probably work, might need to get an adjustable pushrod, which Dr Diff probably sells. And the rubber retainer to retain the pushrod in the MC piston.
A little backyard engineering involved, but not especially difficult.