The copper-based anti-seize compound (C5-A) was made many years ago under the brand Fel-Pro. I still have about half a can that I bought in 1975.
It is now made by Loctite (& others, I think). Google C5-A & you will find many sources. Here is one:
http://www.midwayusa.com/product/723...pper-1-oz-tube