I don't know about the Portland area.... or where these companies base their a/c but here are a few that may be looking for pilots.

www.emergencyairlift.com - these guys are out of Bend, OR.
www.cal-ore.com - out of brookings and somewhere in ca.
www.aeroair.com - out of Hillsboro.

Sorry I can't be much of help.... good luck finding something!