Go for a boneyard car. Should be lots to choose from in the PNW. There were quite a few Cougar/Tbirds in Oregon before I moved away. Also - if you are patient you'll find a clean no rust parts car on Craigs for $4-500 that you could rob from.
If I can't find the rubber, I guess I will see if I can find it on a used car, though that seems less than ideal.