It would be ugly. Unless you have speed, Matt Skelton is going to be an awkward opponent: he doesn't do anything well, except that he has mastered a sport we might call "Contemporary British Heavyweight Boxing", where the objective is to use your weight, inside fighting and mauling tactics to wear down your opponent. Sluggish haymakers are also permissable, though not encouraged. Effective jabbing, foot movement and feinting are positively unsportsmanlike. Buddy Baer was by no means invincible and was not the sort of monster puncher who is going to knock Skelton spark-out. However, I give him the important edge in stamina here. I think he would dominate the later stages, getting either a clear decision or maybe a stoppage win on cuts/accumulation of damage. I think I'm becoming even more ugly by just thinking about this fight.