Welcome to this forum. I see this is your first post on the forum. Did you read another poster's thread about muscle worship in BKK? That post was fairly recent, probably less than one month old. He was looking for the exact same thing as you do. He ended up hiring a white guy in BKK after his failed experience with a Thai guy the first time. Believe it or not, people can get info by doing some homework here themselves.
BTW, @vinapu claims to be the muscle expert in BKK.