[Mrmerlin]

Its a fun exercise, to take one apart.
You will note they are not made to come apart easily.
That said if you value your time ,safety and money follow these instructions

Get a new ATE master cylinder, the one you have should be taken out of service.

A new booster , based on the back of the old MC it has been leaking brake fluid into the booster and or the booster has water in it.

A set of stainless flex lines, the brake lines should be upgraded.

a liter of ATE fluid, with fresh parts bleeding should take less than a liter.

a tube of DC 111 for the grommet bushings. Amazon sells this,

NOTE the DC111 will prevent the inlet ports from corroding.
NOTE you can wash the tank in brake cleaner,
then simple green and hot water rinses till its clean.
Then shake it dry ,
then add a ounce of Iso alcohol and shake it ,
then pour it out,
use a hair drier to blow warm air into the tank to remove the alcohol and water.
Roger has all of these parts