You can get master & slave cyl rebuild kits at NAPA. Any industrial brake & clutch shop can reline the shoes. Take the rubber hoses with you & get them matched up as far as fittings & length. You can go about 1/2 inch longer than stock length without any clearance issues. As Stuart said, get a factory shop manual. The CD rom is difficult to use. Follow the brake adjustment procedures closely.
There are numbers on the right front of the block right below the cylinder head. These numbers will tell you what compression ratio & horsepower the engine is. Look for a markings like 76Y or 79Y. Also contact Pontiac Historic services.
www.phs-online.com For a fee, they can tell you just about anything about your car, date it was built, what options came on it, etc, etc.
An last but not least!!! WELCOME!!!!