Few things to consider.
1. there ain't that much difference between a 20" and the much more common 22" barrels, you would have to go down to an 18" to really have a noticeable difference.
2. There is not much difference between the 7mm-08 and 308, I own/handload both and the difference between a 140gr 7mm-08 and a 150gr 308 is hardly noticeable inside 200 yards, beyond which the superior ballistics of the 7mm kick in. Though with 120gr Pro Hunters the 7mm-08 has considerably less recoil (like a 243)
3. If you wanted to split hairs I would opt for the 308 over the 7mm for the average hunter, ammo costs less (not an issue if you handload) and the advantages the 7mm enjoys are well beyond normal deer/hog hunting ranges while a .30 cal bullet is a small advantage closer in where 95+% of all hogs are killed.
4. If I were to design the "perfect" hog rifle it would not be a bolt action at all, I would go with a light/handy semi auto in 308, 7mm-08 or 260 Rem depending on the conditions I was hunting. The 308 if my long shots were inside 200yards, the 7mm-08 if they were 300yards and anything beyond that the stealer ballistics of the 6.5mm would easily be my pick.
Just some food for thought.