It'll help avoid problems with pecking order if you get a younger/smaller pig, I'd go for a castrated boar as they'll automatically assume the submissive role.
Younger pigs are also quicker and a bit more nimble so they'll be able to get away from her if she does decide to have a go - she might not, she might be very happy to have a new friend.
I'd introduce them of an evening and yes, a couple of cans of sweetheart stout (ours prefer it to Guinness
) will chill her out - make sire the wee one has an area where it can shelter away from her in case it takes a couple of days for it to be allowed into the arc.
Where are you? I might be able to point you in the direction of pigs