If you can't find anyone local, have you given any thought to doing it yourself? There have been a few threads in the past providing help and instructions.
I did the TVS and the elbow on my GT500. Its not really that hard to do just takes more time and patience. You can sit down with a dremel and it will come out the same as what someone else is going to do. I'm also good friends with rick, and does a great job on the vehicles he works on.
1320Junkie, he has been recommended to me a few times. He lives in the Connecticut area. I will be having him port my blower in the spring time. Check his instagram out because he posts pictures of his work
Instagram-->@1320junkie