66 4 spd Console in a 65 Barracuda

The '66 tunnel hump is different from a '65, the consoles themselves changed in '66 to the newer "coffin" style console. Since this console is wider than the '65 console, the bucket seats were also changed and made a little narrower to accommodate the console.
So, to mount the '66 console in your '65; you would need the '66 floor hump (or make your own, they're not that difficult to make since you're obviously not concerned with being 100% factory correct and it will be covered by the carpet and console anyway), the mounting brackets, and '66 (and up?) seats.
When fabbing the tunnel, google up some reference pictures for your application, since the hump needs to not only provide clearance for the shifter (which is offset to the driver's side and requires a special shifter handle/mechanism to locate the shift lever in the "central" location of the console), but for the linkage as well as it goes around the transmission/torsion bar crossmember.