The Northridge stuff is original GI stuff. I've got boxes of them in the past, quite a lot of the boxes had mild water damage from years of storage conditions etc but they were very clear on the descriptions. I even bought some of those and they had no issues, turned out great. Wish I'd bought a lot more. They sell on ebay under norint or something like that, anyhow yes, the stocks are the fat replacement but that's easy to take care of.
Just an observation on stock preference, watch the Keystone stocks, on a couple occasions I've found them to be a little soft. This had nothing to do with Northridge of course but I think Keystone was a little less selective on the blank quality than the others.