The label sounds to be a radio repair service. The 5Y3G is the rectifier, the 6F6G is the output tube. Those two are the hard working tubes, and may have been replaced. The other two 6K7G & 6SQ7 both being Westinghouse may the original. It very well could be a Westinghouse radio. If you can post a picture, I bet someone will know for sure.
The photos can be found at http://groups.google.ca/group/vintage-radio-pic/web/pictures
Gareth,
You only listed 4 tube numbers, but I see 5 on the chassis.
Are there any numbers on the back of the chassis?
Carl T
Carl,
The fifth tube appears to be a Marconi 6SA7. A little difficult to read though!!
Gareth