This is a good idea, MurderDog kind of specializes in the underground stuff, so they'd be more down for this idea more than a major obviously. They did regional compilations for Kansas City and South Carolina, two fairly slept on places so maybe they would do one for the NW.
And again any argument on how much of it is Seattle, how much is Portland, how much is somewhere else out there is dumb. Put the 40 best tracks period, fuck where they're from in the region.