It is a big shop with very pleasant feel to it, and has a very large stock of high quality fabrics for suits and shirts. He does original tailoring in his own workshop on the second floor.
I have had a bad experience with other tailors and this is the only place I can recommend.
Just under the Asok sky train station, on Sukhumvit road.
check out his web page www.moonriverbyvj.com, it will give you all the details.