Yeah, talking about how rich or lean the mixture is just increases the variables in engine performance. I'm a fan of tweaking the timing (I learned it the old school way of doing it by ear, freaks the guys out at the auto hobby shop

). As for enrichening the mix, I'm not a big fan of that, although it works. I think using a better fuel is the right answer, and then setting the timing to get the best spark advance for the desired rpm running range (i.e., if your motor is more of a dragster than an high-rpm runner, it'll be a different timing btdc).
After that, we're talking about gearing, trans, cfm.....man, now I wanna go take my Jeep apart again!