If you end up going OEM, there's a superceded part for the radiator and a few additional parts required for the "swap". I get most OEM parts from
www.subarupartsdepot.com. Give 'em a call and ask for John Gue. Best customer service around. They're east coast but shipping is cheap. If you're in a bigger hurry, try subaruparts.com or subarugenuineparts.com. YOu could also email
crucialracing@gmail.com to see what Jeremy has. He offers aftermarket radiators like Koyo and some that are less expensive than OEM IIRC.