The head with the slot for the standing "Ejector" is considered a controlled round feed and was utilized with the stagger feed magazines. The new style is push feed and can be use with both stagger and center feed magazines.

If you want to use the standing ejector you will need to cut the slot in the bottom of the action. The trigger hanger pin goes through the hole in the ejector.

In this article by Mr. Eddy you will find some pictures that may help you.
http://www.savageshooters.com/showth...bolt-operation