I had a guy up there do some head work for me several years back, I can't remember his name or shop name now but he was off the bypass freeway # 167 from Tacoma going east to Summer and Pacific probably in Auburn at the airport, DON'T use HIM
There should be a bunch of good aluminum tig welders working for Boeing
Which part of WA are you in?
If around Tacoma and Seattle area try contacting one of the Austin brothers, Walt or Buckey, that race hemi motors in blown alcohol classes up their. I'm sure they know the good shops to use and the bad shops to stay away from. I would ask them if they do their own engine work first before asking about who else to use to do your head welding