If you really want to shoot 30 cal subs you will find the 300 AAC case will be easier to work with. 308 Subs always had issues with cold bore flyers for me the 300 operating at higher pressures did not. You can do it with a wider variety of powders in the smaller case as well. 16" is the way to go.
30 cal subs are not ideal hog killers and proper ranging is essential, 1.1 mil drop every 25 yards makes ranging within 12 yards pretty critical.
Back on 2006-7 I went down this road myself after not being happy with 308 sub accuracy, ended up buying a Brux 1-8 blank and put it on a Howa, used remainder of the blank to make a 10" AR barrel. Only the AR remains. This was in the 300 Whisper days but it virtually identical. Rifle is very accurate still to this day, Sierra discontinued my favorite 240 Match Kings but I still have a good supply to get me a couple more years.