Hey, I’m maintaining a thread on Behind The Voice Actors.com dedicated to identifying the voice actors who appeared in the JAL Dub of Porco Rosso. Admittedly I first believed Barry Gjerde was Porco when I first started out, but that was because all previous sources that came before my investigations were no doubt going off unsubstantiated rumours. Barry Gjerde DID state on his old website that he played 4 characters in the dub, but nowhere does he say he played Porco (http://web.archive.org/web/20050209195933/http://www2.gol.com/users/barrygj/profile.htm). His involvement was purely as an additional voices guy, perhaps he also may have translated and written the dub script but that’s the extent of his involvement from what I have been able to find.
I have no idea who voiced Porco in this dub, but it was not Barry Gjerde.