If I replace my stock disk brakes which are on a 67 Camaro that came with a 327 and a 4 speed, what is available for rotor/brake sizes and what works well?

As for rotor size, what is considered large and what isn't?

I have no knowledge here.

you might start by reading the sticky at the top of this forum, lots of good info there. Searching will reveal much too.

http://www.pozziracing.com is a must read

our stock brakes are 11" by 1" thick, with a single piston floating caliper.

The "PDQBCC" setup is popular, uses a 11.75" rotor from a full size car with a pickup truck caliper, will fit in most 15" rims. Some fabrication but cheap to do.

I'm looking seriously at Wilwood. They make good stuff.

Most of the others, such as Baer to mention one of many, use various combinations of fourthgen F body and vette factory hardware, 12 and 13" rotors and Australian PBR 2 piston floating calipers. 12" will fit in a 16" wheel, 13" needs a 17".