That is a common boa. Most likely BCI. I hesitate to say Colombian though due to his dark coloration. I am going to suggest that there is some Nicaraguan or Peruvian influence. Perhaps Argentine. But my guess is Nicaraguan. The pissy temperament lends to Nicaraguan too.....
The best way to calm down a touchy boa is simply with patient and persistent handling. Be gentle and calm, but don't give in and don't put him back just because he nails you. If you have to, hook him out of his enclosure and then just lay him in your lap. They do better on a lap than trying to set them on a bed or floor and then trying to pick them up from there. Just start out with him in your lap. Eventually, he may get calm enough that you can watch tv with him. It sounds a bit silly, but seriously, that is good bonding time. Just remember - patience and persistence.
He is very pretty!! Kudos to your friend for rescuing him!