The Anaheim pepper is a low heat offshoot of the New Mexico pepper No.9 developed by Fabian Garcia
http://en.wikipedia.org/wiki/Anaheim_pepper
These peppers are usually called Numex types. I don't know if there is an actual Anaheim cultivar commercially grown any more (the cultivar name gets changed to "Anahiem" on the package). Numex 6-4 was the basis for the New Mexico green chille industry for many years, Big Jim and Sandia are the next steps up in heat level from Numex 6-4. Sonora (sometimes called Sonora-Anaheim) is a large low heat anaheim type, and probably a good choice if you are looking for low heat for stuffing. I grew seeds from a package of dried anaheims and they were much smaller and less regular in shape than the Sonora.
The University of New Mexico Chile Pepper Institute has some good information on varieties through their shop if you download th PDF catalog
http://aces.nmsu.edu/chilepepperinst...l#anchor_23260
You can find Sonora and many other numex types at tomato growers supply
http://www.tomatogrowers.com/
Stay away from Reimers Seeds. They have a good selection on paper but most pepper growers say that their seed is bad and often mislabeled.