Ossumpei, if you're just tweaking your main chili recipe, I'd recommend that you make a large batch of what you consider your "mother" recipe. Then separate it into a few smaller pots. Label each pot by number and write down the extra ingredients you put into each one, that way you don't have to create from scratch over and over again and you can taste and compare in real time, both immediately after cooking, as well as the next day.
Also, Mexican Chocolate is nothing like cocoa powder, they couldn't be more different. Mexican Chocolate is sold as "Ibarra" Chocolate and you can buy it at Whole Foods and other specialty stores, or online. I recommend buying it and trying again. Cocoa will never give you the same rich texture and flavors that Ibarra will. Good luck!
Ibarra Chocolate online:
http://www.mexgrocer.com/2544.html