You have a standard shank based on your model caliber combination.
Use your lug. It is not even close to flat but you can always change it if you get a new stock.
If you decide to go blind you nailed it. Your bottom metal should fit an aftermarket stock with a Savage DBM inlet. Educate yourself with JPDown's informative article here: http://www.savageshooters.com/conten...Parts-Tutorial