Is your car a JDM one, or an Aus-delivered unit? Australia/Europe didn't get the 7M-GTE until the 1988 model year (production starting in 08/87), however Japan had the 7M-GTE from day one, in fact Japan never had the 7M-GE in the Supra, ever.
The interior colour is a bit more rare, but it isn't so uncommon people don't know about it. It was used in Japan and export models from the get go in 1986.
From your serial number, your car was made in 09/1986 which would move it into the "1987" model year.
I don't recognize the paint. If you can post a picture of the data tag, it would be much appreciated! (For the model code, paint code, interior trim code, etc.). I'm pretty interested in it.
Jeff