Fairly simple conversion. The toughest part will be locating the bolt head. If ordering parts from Savage, use serial #H800634. You'll need the 7.62x39 bolt head, Savage part number 108659 - you will most likely have to source a PT&G bolt head as Savage no longer sells them.
Youll also need the 7.62x39 magazine box, part number 108664, and the 223 follower, part number 106253. That should be all you need besides a barrel, headspace gauges, and removal/installation tools.