Here's what I remember:

70 = Rochester products
29 = 1969
2 = 4MV Carburetor
6,7 = Pontiac
Last didgit = specific application. Even # is AT, odd # is MT.

after 1973 or a974, they added a "1" in front of the part number. Check out:

http://www.teufert.net/pontiac/carbs.htm

Your carb is worth $1000 if it is restored, and $500 if it's restorable. Don't trade it for the one you need, whatever you do. Keep it or sell it to someone with a Trans Am. There are two other codes there. One set of two letters, i.e. XD and a four digit number, such as 2778. The four digit number is the date code. Number of day followed by last digit of year.

Q