Here is what I found. The master cylinder has a snap ring. I have others with the two bolts they are manual brakes.
The power unit that is here has an aluminum piece with a rubber gasket . That piece is laying on the vice and seals the booster to the master. I have a picture as it was on and with it off the master. Here are some pictures I took of the manual and power brakes. I don't need this power unit or master. It has the factory brackets also if you or someone wants it just pay the shipping. I can glass bead some of the parts if needed.
It looks like the manual brake master has the ring that holds a boot. I know the master I put on the Duster has a plastic gasket the holds the boot. The 67 manual master the piston support with the two bolts holds the boot. Look at the pictures.