Should be just redrilling the screw holes and cutting a new slot for the recoil lug. . . Probably some bedding and fitting around the trigger too and maybe the mag box? If the new stock is set up for DBM or an HFP, probably better off to just cover the opening than to try and use it. You'd have a blind mag set up then.

May look into Stockade stocks also and see if he can help you too. He's on par with HS I'd say, or better for Savage's since that's his specialty.

http://www.stockadegunstocks.com/

Adam