A total of 257 units were built with parchment trim/interior.
Only 20 were GT350s. The majority were Big Blocks ('BB' as JD mentioned, also an acronym for Brittany Blue)
The Shelby VIN sequence range was much wider than 0675-0725. However,
Ford SJ build dates for parchment trim was limited to January 1967 until March 1967 with one unit exception in May.
Typically each DSO was built with the same engine/trans package and trim color. They only varied in paint colors.
There were a few DSO exceptions as JD noted above. Those were DSO 84-2534, 2536, 2538, & 2540
(An SRG topic lists the in depth details)
https://groups.google.com/g/shelbyresearch/c/43mJlQH5qL0JD, all 15 units in DSO 84-2539 had parchment trim.