For that year things are pretty strait forward. First, remove the old master making sure that there is no damage to the lines and fittings. Next, if you have a bench vise or way to clamp the new master on a bench that will help. Fill the new master with fresh d.o.t. 3 or 4 close the lid and with the master clamped in the vise and the exit line blocked ( use old fitting with the end of a small line crimped to block the exit or out flow ports ) push in the rod all the way and then bleed the 2 ports. This is called bench bleeding to get any air out of the master. Make sure to always top up the master. A couple of times should do the trick. Then install the master in place. You will have to bleed the 4 wheels after this. Start with the furthest from the master to the closest. Check pedal after. Job done.
If you are not familar with brakes it may be best to have a certified technician do them. You can purchase a Haynes Manual and it has all you will need to know. Brakes are the Most Important feature of the automobile and need to be right.
I would suggest you get a service manual such as the factory service manual, a Chilton or other manual. Therein you will find instructions as well as diagrams that will help you change your brakes. If you don't have a manual they are often available at your local library.
It may have either manual or power. I am not sure if the factory put them on but I have seen them with power brakes. To tell if you have MANUAL brakes look for the master cylinder ( this is where you add brake fluid ) and see if it is attached to the firewall directly. if the master cylinder mounts to a some what large round unit with a large black approx. 1/2 " diameter vacuum hose attached to it it is POWER brakes.
That should be a timing chain. The answer to the question is quite lengthy to answer. Purchase a Haynes Manual and it will give you illistrations of the procedures.
Buy a service manual and read it.
If you don't know how to do the brakes you really need to get an instruction manual from the parts place. Brakes are a safety item and you shouldn't change them unless you are sure of the procedure itself.
Drums are not a job for beginners. With the right tools & a manual you could do it.
If your power brake booster (the large roundish metal thing that the master cylinder is bolted to) either fails or loses its source for vacuum then your brake pedal will become very difficult to push like if you have manual brakes.
Get a manual on your car and do the job correctly the first time..
Go to NAPA and buy a Repair Manual.
get a chiltons repair manual for chevelles and read up.
abs = Anti Lock Brakes,,,,,,,,,,,,,, This is not the stopping brakes, its the NOT stopping brakes. Your anti lock brakes are not working. Its A computer and A pump with sensors, You need to take it to A GOOD shop to get it fixed. Not A cheap shop A GOOD one. This guy is a fool, you need to look in your service manual and look up your anti-lock brake system, then turn your car on and count how many times it flashes before it finally stays on. My camaro does the same thing but i dont have a service manual but it flashes once the stays on, then look that up in the service manual and that will tell you whats wrong and what you need to do from there.