65 Barracuda question
The original tire size would have been 650/13. Even Commando 273's got 13 inch wheels when ordered without the Formula S package, even if they also had the rally suspension option.
I'm pretty sure that some stripes were dealer installed (or, more accurately, dealer painted, since the stripe was not a decal). If I'm right, this car could have had a stripe when first sold, even if it's not on the fender tag or build sheet.
One of the biggest clues that this Barracuda did not originally have a Commando 273 is that there is no rectangular cutout at the lower left side of the rear valence for the Commando 273's cowbell resonator.
Finally, I would note that the rocker trim on this Barracuda is from a 66 Barracuda. The 65 trim is narrower, and does not extend to the bottom of the rocker. For this reason, the wheel opening moldings 64-65 are different than 66, as the 66 moldings have a larger cutout for the rocker trim than 64-5.