In that era they primarily used Victoria Luggage for the tolex cases, and occasionally a company named Decuir. Lining colors were not specified, so they got what they got, blue, black, orange, red, yellow/gold, etc.
The only way I can identify Victoria Luggage and Decuir cases from early G&G (they spun off Victoria Luggage in the very early 80's) is by some of the hardware. The center latch will be shield shaped and the handles will be leather covered metal. They also have a shield shaped pull tab on the accessories compartment, but earliest G&G's have that as well. G&G usually used a plastic molded handle, but in later years they used a leather covered handle as well as an option. Though they are not exactly like the VL and Decuir (they are actually nicer).
Also important to note is they had the cases tailor made. The cases have a matching lined insert made to fit the shape of the lower area of the bass. However, this insert sometimes falls out or is removed. Aftermarket and most otther brands using the same manufacturer cases never have the insert.