I personally would go for an older more sedate boar if you can find one that he likes. This is what I have always done in the past and I wish that I had been able to find an older boar that Jack liked as I have had a big problem this weekend with Jack and Hector - they got on amazingly well at for months, lots of snuggling and lying down together, (and Hector at 8 weeks old was literally the only piggy out of loads that Jack would tolerate, I even tried other babies that he did not like) but suddenly, out of nowhere, Hector and Jack had a really scary fight on Saturday.
It has been followed by lots of chasing by Hector of Jack, and Hector humping Jack constantly which Jack absolutely does not appreciate and he has retaliated with minor nips. There has been lots of raising up on back legs, yawning and teeth chattering. It is always instigated by Hector.
They are currently side by side with a divider as I cannot risk a major fight escalating whilst I am out today.
Jack is 16 months old and Hector is 6 months old (so Jack is quite mellow now, whereas Hector is at the peak of his hormonal surges)
I'm hopeful that it is not the end of a beautiful relationship for these two

but I wish that I had been able to find an older boar as I do feel that would have been a more stable bond for Jack, without the risk of teenage hormones causing problems later down the line!
Good luck
Cassandra