Bigger piston size is 2.75". The Smalls are 2.6". If the rumor is true, you should already have the 2.75" being a 76.
I have never had an issue with phenolic pistons. My 12 year old A-1 Cardone remans that were $9.99 each still work perfect (just replaced the pads and rotors last week). They are also lighter.
Summit is the cheapest place online to buy rotors once shipping comes into account. The Bendix rotors are still made in China, but the quality seemed ok.
I used Wagner Thermoquiet Semi-Metallics...they are just barely bedded in, but they work well and so far are quiet. I also went to the 11.75" brakes though you may not want to go that route since they don't clear 14" wheels. It is a nice upgrade.
Make sure you get new brake hoses!!!! Also, if your master cylinder looks rusty on the inside, put a new one on, otherwise you'll just be pumping crap into your new parts.