I know we've been "down this road", but it cannot be stressed enough. You did NOT install the gears incorrectly. You installed the the distributor incorrectly. "By the book", the settings are 12/12 for BOTH Pontiac AND Chevy. While it may SEEM "easier" to install them ar 6/12, it really isn't once you understand "where you're going". But when you DO put it at 6/12, rotor points to #6, as others have stated.
Please, this is not a point of "contention", but a point of service. I've seen more confusion over this specific issue on these "hobby" sites than any other.