The only place here in WA that I can think of to ask is Brads Custom Auto in Seattle (I think that is the name, and I think they're in Seattle). They have a pretty wicked autocross car at the B.C.C. Mustang show each year, and they have been very helpfull/knowledgeable each time I have spoken to them.
Might also call up Jim Greens in Lynnwood to see if they will do porting, or know somewhere who will. Also, I think the Mustang exclusive shop (used to be Mikes Mustangs, or at least some of the same guys who worked there) is still in Marysville/Everett.
Guess I could think of more than one place.