I'm not totally up to date on pig breeds but I used to be and I've seen a few next to dogs of various sizes..
Pot bellies get MUCH larger than most people imagine. If you have another, smaller, breed in mind please say so..
I have seen piglets of "meat" breeds at 50lbs that rivaled or were obviously larger than 50lb puppies (great pyranees).
By the time the pig reached 150lbs the dog was smaller but LOOKED and, by force, felt smaller, it was no contest. By the time the dog reached 150lbs the was HUGE.. I think 230lbs. Anyway, we got other pigs later and the younger pigs approaching 150lbs were harder to deal with than 200lbs of dog.
A medium to large dog = 70-100lbs
a large dog = 110+lbs
A medium to large pig = 150-280lbs (at market weight, possibly 2 years before ideal breeding age)
A LARGE pig can easily top 1000lbs
Know the breed, know the lower and upper limits and plan for the UPPER limit. If it "could" get to 150lbs, assume it will and it will be like having a 200lb dog that knows how to open cabinets and is smart enough to train YOU to give it treats.. They are smart.
I've also had to wrestle a sedated 60-70lb piglet and it was NOT FUN.. We had 4 people restraining it and a vet trying to make 2 sutures and it took almost 2 hours.. he was worried about the sedative and painkillers wearing off by the time we were done and this was a very wel trained pig..
I asked my husband and he thinks a 75lb pig would be way more destructive than a 150lb dog and forbids me from having said pig. Will allow a 200+lb dog, oddly enough.