How are you determining it was built in 1969? Ford sold a handful of 1600GT Capris in January 1970, after which the GT badge transferred to the V6.
Even if it was assembled in late 1969, you’re better off referring to it as a 1970 Capri because that’s essentially what it is. As you’re looking for parts for the rebuild, you might confuse people who think their parts won’t suit your car. There are some differences in parts between 1970 cars and the 71/72 cars, but not everything differs.
Re: the gearbox you removed from your car, it isn’t the standard one fitted to Mk1 V6 capris. It’s most likely an upgrade by a previous owner who wanted a better shifting gearbox than the original side link Type F. I think I saw a photo of the box you have on Facebook, and it looks like a Ford Type E which may have been fitted using bellhousing from a V4 Essex engine (little brother to the V6 Essex capri engine we got). It has the same 1” / 23 spline input shaft that the standard V6 capri gearbox (Type F) has. In the end, without knowing what car the gearbox came from, it will be quite difficult just going off the numbers on the gearbox.
Cheers
Jamie