I owned a 64 1/2 about a dozen years ago, brought it back to Australia, it was the 148th one built. It was a numbers matching & had a 289, 4 speed, pony interior. Many of the first mustangs had either 6cyl's or 260 V8s and some had 3spd manuals.
It was first registered middle of March '64 which was about a month before they were offically released, some trim and exterior were slightly different to the released version and no it had the original interior, the only external difference was a Hurst 'T' handle shifter and dragway mag wheels.